I have seen other posts on this forum asking about how to learn Ancient Greek using LingQ, since there is no slot for it and it would be confusing to mix ancient and modern Greek. There are also a litany of other languages (historic, constructed and niche) which will certainly never get a dedicated languages slot on LingQ (e.g. Klingon, Cornish, Low German, Elvish).
With modern AI, I am wondering if it would be possible for LingQ to offer a more bare-bones, custom language slot to users which would essentially allow you to pre-programme an AI, which assists in translation/LingQ creation, to any language you want: perhaps you could enter the language, a more detailed prompt/description of what the language is and perhaps some sort of basic reference like a dictionary or a file containing grammatical rules. Some functions on LingQ might have to be switched off, like sharing created LingQs between users, social functions and auto-translate, but the core framework and activity tracking of LingQ would remain in a limited form for any language of your choosing.
It is worth mentioning that the benefits would probably be very limited for dead, pre-modern languages with very little available media or which never had formalised spelling/grammar rules. Nevertheless I think this could create a new niche appeal for LingQ, granted expectations were realistic.
This is not a serious feedback/suggestion post. I am simply intrigued at the idea and wonder which languages you would be interested in learning if this feature existed. I would probably use it to learn (the Mercian dialect of) Middle English.