Good luck, I hope it works! Consider adding some flash cards with grammatical forms to mix in with your "character" cards. e.g. a monadic hook "(f g) y" is equivalent to "y f g y". And some short idiomatic phrases, e.g. "(#~ f) y" means -- approximately! -- "copy the values y_i of y wherever (f y_i) is true." You can find examples of these little phrases on the J wiki.
Thanks. It's still an experiment, and about to be restarted (was going to be learning modern C++ and some APIs for work, but direction shifted and I'm now on a Java project, which I haven't used in a long time). I'd actually like to try this for J, but work and Spanish (to speak with the in-laws) are my personal priorities right now. Perhaps in October I'll start studying J to use for this next Advent of Code. I have been getting the itch to relearn it. I learned a large chunk of it circa 2010, but haven't touched it since, then APL in 2015 or 2016. I've never used either professionally or for a major project so a lot of things have been forgotten.
I'm basing my experiment on what I learned using Anki for language learning. Much like you said, you need larger statements and to develop an understanding of them. For Spanish I have some loose writing/speaking prompts and some reading prompts (not copying the text, but a prompt to go to today's newspapers and read some articles and explain them to my wife or to read some paragraphs from a book). How well I can complete these without needing a dictionary or to ask for assistance determines how I mark the cards. It seems to work decently, they come up almost like pop quizzes in school classes since the spaced repetition system means I don't see the same prompts each day. I think it should work to have project prompts for programming languages in the same manner.
