My German peaked during an exchange, where after a few weeks of it "washing over" me I was using the language more naturally, even if still making frequent errors. Equally my French peaked when I was working around lots of French tourists, so I'm very onboard with this exposure-based approach.

Nuenki is pretty much what I was looking for - plus it's a good shove to make switch from Safari to Firefox (a change I've been meaning to make).

I've heard of Anki as a learning tool, but not tried it. What makes it miserable?

I'll be sure to checkout the Reddit and YouTube links too. Thanks for the help internet stranger!