I selected Lapin as my speaking language, then wrote a line on my practice paper. When I read the paper, even without Lapin selected, there is a "Lapin" indicator on the paper (although it isn't lined up with the line I wrote in that language, maybe that's its own bug? Not sure it that's intended. All the languages I've written in on that paper show up in one short list, so maybe it's just tagging any language present on the paper.)

Anyway, the confirmation was that I used a skill book on Lapin to increase the skill, then to test, I tried to use another. It said "you need to use that skill 3 more times." I then read my paper, then tried to use the book again, and it said "You need to use that skill 2 more times." For further testing, I also then wrote a new line in Lapin, at which point I was notified I've used it enough to learn more. I think this means it counted my writing as 2 uses.