I’m currently reading through Yates work on Giordano Bruno and getting somewhat annoyed at how frequently they’ll reference just a section of the quote or just include it as a reference to something they said. There are even footnotes where the only thing included is a sentence or three in Latin alongside the citation. While I have managed to find translations of some of the works mentions but very frequently I have been relying on my cursory knowledge of the language and my short stint in highschool studying Spanish. At the very least my work translating this will go quicker soon as Apple is releasing the ability to pull text directly from a picture so I won’t have to also transcribe the Latin into a translator. Did authors in the past just expect their audience to understand Latin or does this practice still happen today?
I have had to work with some texts leaving in the original Latin and from what I have had to deal with it is a professional concept of "I know what I am saying here, but I want you to have the chance to see if you agree if you can read it." This isn't done with just Latin texts as often there lacks a proper translation regarding what was originally said and it is best to offer up what the original text has just in case there is more context that a more versed reader might pull from what the historian is talking about.
I often deal with Old Norse, Old English, and Middle English texts and one of the best examples I can think of is when Aud is called a blaudr from Gilsa's Saga. One translation has it where the bounty hunter says "seize her although she be a woman" and another source has translated it as "seize the bitch" after Aud broke his nose with a sack of silver coins. The likelihood of a Viking bounty hunter keeping his cool and calling her a woman would be very low compared to the alternative.
This is also true for some Old English texts regarding the desert monks and the double meaning of words. For someone of the laity they could have easily read the desert father's words as he walked across the barren land in search of God or he shepherd across the land with God's grace. This actually happened in my class as the assistant instructor had read it as the former and I had read it as the latter. Why? They had focused their educational background in English and literature while I had focused into religion and history. We saw different things and the original text was necessary for people to understand how we came up with two completely different answers that were both correct.
As for original authors expecting you to know Latin from what I have dealt with the answer is traditionally yes. Almost every Old English text I have worked with will have Latin mixed in and if you are not ready for that Latin it will throw you for a loop for a bit while you are trying to figure out where the Latin begins/ends and were the Old English is. Even though Latin was dead by the Medieval era it had such strong connections with the Catholic Church and a continued desire to be the inheritors of the Roman Empire's will Latin stuck around as the educated person's language.
I do find today that there is less expectations for people to know the Latin readily, but there will be some texts that still expect you to see the Latin and try and get you to use it over any translation options. Largely up to the author and possibly the publisher due to cost.