Wrote you a ginormous thing but lost it (three times now), being behind a recently hyperactive Great Firewall. Probably for the best, it was way too long.

Some work has been done on issues relating to your question, but for the most part Manchu translations didn't contribute much in the way of preserving or interpreting pre-Qing texts. There were millennia worth of "indigenous" traditions in place, dedicated to the preservation and interpretation of the Wenyan canon (as in, texts written in "Classical Chinese"). Obviously not everything was preserved, and the interpretations were/are in a constant state of flux. Recognizing the not exactly surprising fact that there are certain ideologically dominant readings of the canon specific to the Qing era, and acknowledging the quasi-bottleneck of the so-called Qianlong Inquisition, Manchu really wasn't in the position to save anything that wasn't gonna get lost anyway. The traditions of textual criticism and interpretation, and compilations of texts into anthologies, were as strong as anywhere else worldwide, and there probably wasn’t much of a need for a Qing-era Rosetta Stone to begin with. Not what you’re asking, but I have a personal concern with how the large-scale Chinese-Manchu translation projects have had an arguably negative effect on the preservation and interpretation of the Manchu language itself.

Manchu had a limited role in "interpreting" pre-Qing texts during a brief period towards the end of the empire. Foreign scholars would, for a time, first learn Manchu and then use it as a crutch before going on to the much more demanding task of studying Wenyan. Condensing an extended riff on the history of Manchu Studies abroad [Beatrice Bartlett, Erich Hauer, and Mark C. Elliott (among others) all have important articles on the topic], after this brief heyday, we then had the cataclysmic events of the fall of the Qing and World War I, and most of the planet went into nationalist mode. Interested parties were attempting to imagine "China" as a nation-state, and the ultra-nationalist 'sinification' myths took over. Manchu then became written off as a language of little value, and the going assumption was that any Manchu text you could get your hands on was simply a translation, better approached 'directly' through its counterpart Wenyan original.

Along with the cross-disciplinary questioning of everything in the 1960s and 70s, and indebted to the accomplishments of earlier Japanese researchers, scholars like Joseph Fletcher and James Bosson began to restore perceptions of Manchu's value as something worth studying in itself. Actually sitting down with Manchu, it turns out that the translations aren't always so exact. Going in either direction, content can sometimes be obscured, or added or removed, or deliberately rephrased, depending on the intended reading audience.

Important work influenced by the scholars of this period that touches on what you're asking includes Laura E. Hess' "The Manchu Exegesis of the Lunyu" (1993) (the Lunyu being the "Confucian Analects"), and a number of articles by Stephen Durrant, such as his "Manchu Translations of Chou Dynasty Texts" (1977), and "Sino-Manchu Translations at the Mukden Court" (1979). Quick note that although Durrant has since become focused on Han-era historiography, he was New Qing-y before it was cool.

Close, informed readings of Manchu translations like Hess and Durrant's don't find much evidence of rigorous attempts to unmask the true meaning of the ancient masters. Instead, what's revealed in these readings is vestiges of centuries of attempts by Inner Asian empires to deal with their neighbors to the south. Manchu translations of technical "Confucian" terminology didn't, for example, require the invention of new words, since the concepts involved had long been grasped by the northern peoples and appropriated towards their own specific purposes. Manchu versions of pre-Qing texts are overloaded with borrowed Mongolian vocabulary, because Mongol rulers and scholars had been studying, and even participating in, the Wenyan textual tradition for hundreds of years. Durrant is particularly interested in the enormous influence of the Mongolian filter through which anything describable as Manchu "sinification" necessarily had to pass [for an early ultimate statement on this phenomenon, see David Farquhar's "Mongolian Versus Chinese Elements in the Early Manchu State" (1971)]. Hess uses the techniques of historical linguistics to trace lexemes back to Turkic and Khitan rule over the southern peoples. From an even more obviously utilitarian angle, the order in which texts were translated into Manchu showed little regard for a given work's prestige or centrality to the canon. Instead, texts were translated for their perceived usefulness to the occupation. In these early Manchu translation projects, we can detect very little evidence of a motivation to come to some profound understanding of the classics, much less some drive to "become Chinese." At this point, translation into Manchu was but one aspect of the overall strategies of empire-building.

Later of course, as the Qing settled, an awful lot of things changed. These changes included the approach to the task of translation. There are a couple of comments over here that deal with the use of Manchu during the Qing (and since) more generally. I still owe /u/JSTORRobinhood a response, but one of my main gripes there is how "revived Manchu" today has become not much more than a form of encoded Chinese. What I'm sorta also trying to get at is how this codification process was long underway well before what we'd today refer to as the decline of the Qing. As some of those articles mentioned in that thread demonstrate, in the Chinese part of the Empire, translation work was handed off to Hanjun Bannermen and other non-native Manchu users, who were charged to learn Manchu by rote as a second language. This was simply a demographic necessity, not unlike how the vast majority of the soldiers fighting the mid-17th century wars of conquest were also Chinese.

Putting it bluntly, the work of these translators and clerks and memorialists can’t always be trusted to be examples of 'proper' Manchu. Translations were often direct, mechanical, one-to-one glosses of whatever the original Wenyan intention was. A famous example of this is the once long-held, erroneous notion that one of the Manchu reign titles for Hongtaiji, the Qing Taizong Emperor, was 'abkai sure.' The so-called "real" reign title should be 'sure han' (titles for reigns previous to the Qing foundation in 1636 are later additions to the historical record). The incorrect 'abkai sure' originates from some anonymous translator who, upon coming across the Chinese name 天聪, simply translated each character word-for-word into Manchu- apparently unaware of the official name for the reign. There is an alarming amount of errors of this nature to be found in Manchu texts written by non-native speakers and, again, non-native speakers produced a massive amount of Manchu-language texts. In the PRC, we still often use these translations from Chinese as study material when learning Manchu, which reinforces the idea that Manchu and Chinese are somehow extremely similar, and that you can get away with just mirroring texts word-by-word.

In other parts of the Empire outside of China, Manchu fared rather better. In regions under the jurisdiction of the 理藩院/Lifanyuan, including Mongolia, Xinjiang, and Tibet, a highly official and formalized Manchu was used until those areas began being forced into Chinese-type provincial administrative structures. Manchuria was run almost entirely in Manchu under a separate, unique administrative system. This was one of the few regions where Manchu was, for a time, allowed to develop 'organically,' and documents from Qing Manchuria can read a lot differently from the translations coming out of Qing China. But later on in the empire, Manchu speakers like those stationed in the north weren't tasked with translating Wenyan works. There isn't much hope that the later Manchu versions of Confucian or whatever classics will contain deep insight into the true interpretations of ancient texts. Not unlike how it can unfortunately still work today, the terminology, word choice, and interpretations involved are usually more reflective of whatever dictionary or other reference works the translator in question had at hand.

We're painting a fairly dismal picture here, but I don't believe that the actual purpose of these translations is well understood. This is speculation, but by the Qianlong period analyzed in the David Porter article raised in those other comments, if it was simply expected that Manchu translations of these kinds of works 'should' exist, that's a pretty Qianlong-like expectation. Unlike, for example, the introduction of Buddhism through Wenyan translation, no tradition arose of discussing or interpreting pre-Ming texts directly in Manchu. People seem to have made these translations and then just moved on, and academic translation in the PRC works in a similar manner to this day. The one possible exception of a text 'saved' by Manchu that I can think of at the moment is a Kangxi-era anatomical textbook often referred to as "The Manchu Anatomy." There's a quick bit on this text here, and I don't really have much of a grasp on the history of this thing, but the original seems to have been written in Latin. Even from that one image, it's clear that whoever is translating this into Manchu (possibly the Jesuit authors themselves) is coming from Latin via a Chinese route. The Manchu reads like a translation, but if there was ever a Wenyan version of this text, it appears to have been lost.