[bobthepanda]

A lack of native speakers can inhibit context. How many translations exist of, say, the Aeneid, or Beowulf?

If Manchu didn't need to be protected because of how widely known it is, the notoriously assimilationist PRC would not be launching an initiative to translate all the documents, and would not be promoting Manchu language use and education[0]. You don't see similar efforts with, say, Shanghainese.

[0]: https://www.scmp.com/news/china/society/article/1982570/quie...

[Mediterraneo10]

Language changes, and texts that were written before in a language are not necessarily intelligible to native speakers today. 2000 years after the Aeneid was written, ordinary native speakers of the language it was written in (i.e now French, Italian, Spanish, Romanian, etc.) are unable to make much sense of it, let alone provide valuable insights to scholars. It is trained non-native speakers who are able to read it at all.

Similarly, even if Manchu had not become so moribund, its native speakers probably would have been no more proficient in Qing-era texts, especially considering that they represent an elite literary style and bureaucratic terminology, than trained non-native speakers.