The answers linked by u/y_sengaku can give you an idea of how little contemporary written sources have to say about the religion of the speakers of Germanic languages in Continental Europe. I'll try to integrate that information with a specific example, so that you might be able to "get the general feeling" of Early Medieval Latin sources on the topic of pagan religion and see for yourself what kind of problems they pose to this kind of enquiry.

The example in question is, chronologically, the very first mention of the deity known as Woden, linguistically adjacent to Norse Odin. It is found in an hagiographic text, the Life of st. Columbanus, written by Jonas of Bobbio in the 640s, about events that happened 50 to 30 years earlier. Jonas wrote that his hero, the Irish abbot Columbanus during his stay among the Alamanni, near what now is Bregenz had run into a pagan ritual celebrating Woden, "whom, as other say, they affirm to be Mercury". The locals had a large cask of beer and told Columbanus that they were going to make an offering of it to Woden. According to Jonas the saint blew his breath on the cask, which broke apart and then rebuked the pagans, who for their part simply remarked that Columbanus clearly had a lot of breath. (Jonas, Vita Columbani, I, 27. Ed. Krusch, B. MGH, Scriptoreres rerum Merovingicarum, 4, p.102. English translation in O'Hara, A. and Wood, I. Jonas of Bobbio. Life of Columbanus. Life of John of Réomé and Life of Vedast. Liverpool University Press, 2017, p. 159).

This is a typical seventh-century miracle narrative. Jonas's goal in writing this was to show to his audience, mainly composed of other monks, what a great guy Columbanus was. He had little interest in documenting cultual practices of the pagans: Woden and his worshippers are simply convenient antagonists for his hero to overcome. Nevertheless, we get little tidbits of information that have to be weighted against other contemporary evidence, both written and archaeological. For example, O'Hara and Wood, in their commentary to this passage (note 350 p. 159), discuss how the bit comparing Woden to Mercury relates to other texts and an artifact from the same area and the same period known as the Nordendorf fibula which mentions Woden and Donar.

Even so, it's hard to draw any conclusions. I'll stick to literary texts, as I am not very well versed in archaeology, so that you can see what other difficulties arise. The next literary narratives to mention Woden are of Northern Italian origin and describe his role in the founding myth of the Longobards. These texts are the so called Chronicle of Fredegar and the Origo Gentis Langobardorum, both from the 670s as well as Paul the Deacon's History of the Lombards, written at the end of the eigth century. Out of these three only Paul's later text picks up Jonas's equivalence between Woden and Mercury. Where does it come from? Such an equivalence is part of the tradition of Interpretatio Romana: classical Latin authors, for example Tacitus or Lucanus would not mention the proper name of foreign deities but they would "translate"it to the closest Roman equivalent. Now, in Paul's days Latin classics were easily available to scholars of his caliber: it is likely that he would have picked up from his models the habit of Interpretatio Romana as a stylistic flourish. On the other hand, while Jonas had a remarkable degree of literary skills, he was probably less familiar with the likes of Tacitus. Whatsmore, as O'Hara and Wood also remark, the phrase equating Woden and Mercury is not present in all of the surviving manuscript copies of his work. It is possible, though not certain that the equivalence had made its way into later copies of Jonas's work because of the influence of Paul's later text. So, in summary, not only we are in trouble trying to place Woden in a pagan context on the basis of Christian sources, but we are also in trouble when we have to ascertain how a certain Christian author perceived it: we can not be 100% sure if the equivalence between Woden and Mercury belongs to Jonas or to Paul.

As you can see collating various bits of evidence is absolutely necessary if we want to have even a little bit of certainty when investigating this matter, and all the same we are on very shaky grounds. Add to that the influence of nineteenth-century romantic nationalism which has forever left its imprint on "Germanic" matters and you can see how the interpretation of every little detail of this topic is a veritable minefield.

While more can always be said, I listed some of relevant posts, including the information on the extant written evidence, and posted in: How much do we know about Anglo-Saxon and Continental Germanic mythology?.