We do get a lot of requests (and very kind offers) for this. But yes, what everyone said. It’s quite the undertaking, and it’s not even just writing new mnemonics for everything (and making sure the quality is there, too) but it’s maintaining them (every time we add something or move something), editing them (when someone’s kind enough to let us know we made a mistake in the copy, or even when we realize we wrote something kind of rude). I do feel for everyone who wants something like this in another language, but it is pretty far beyond what I think we could realistically take on.
That said (and this is very much in the “only talked about this, don’t get any hopes up” stage), there’s potential for a future where we better support your own custom mnemonics. And then, yet another potential future where we let people share their custom mnemonic sets. Though, with sharing we have to think about moderation — which, again, gets really tough for us when it’s a bunch of languages we don’t speak.
For right now, you can use the note fields in Lessons to write up something for yourself, though. And, while that’s a huge amount of work, there’s nothing better than creating and writing your own mnemonics, at least where recall strength is concerned.