Yeah, I took a look at it when it got linked on metafandom (which is how I got to this one as well). I'm not sure I saw anyone who was completely incapable of writing decent prose in their mother tongue (as opposed to not doing it for canon-compliance reasons or because the readership is better in English), though. I honestly just can't write decently in Spanish anymore. Meta, essays, that's fine, but prose comes out robotic.

What I do find fascinating is that there are (predominantly femslashy) fandoms for a couple of Spanish TV shows (that I don't watch) in English, but AFAIK there is no Spanish fandom for them. Not the kind that writes fic, anyway. (I'm aware this is also the case with a bunch of other gay storylines in European TV in general, mind you, I just find it... interesting.)

I've actively searched for fic in other languages before, but I really don't know where to look and don't want to wade through pages and pages of crap on an archive for five minutes of entertainment.