In particular, something where you can paste in a conlang specification (ideally one created since the model was trained), a sample text, and it will just spit out a basically correct translation into the conlang. I'm not counting something that requires lots of effort (with prompt and follow-up responses) to get working.

It must work on multiple conlangs with "interesting" grammars (i.e. it wouldn't count if it only worked on relexes of existing languages). The model must be one I am able to get access to or otherwise test.