I think a general auto-translation feature is kind of out of scope of this extension as translations are best handled by dedicated translation models and not LLMs. From my understanding, in particular "open" LLMs that you can self-host aren't that well-suited for translation tasks. There is an existing DeepL Application, I think it should be possible to adapt that code to work with Libre Translate instead if this is what you imagine.

Now for more complex features where you would provide additional input, it might again be better-suited as you can provide additional instructions. For example, the update feature could provide both the updated page and the existing translation as input, maybe even with annotations what was changed and then the LLM could produce an update that takes the existing translation into account to only change what was actually changed and to keep the style of the translation or how certain words have been translated.