With the power of my new stew, and deciding to run away then fight rather than just storm forwards, I completed the mission I was stuck on (where you have to beat Gong to a caged Patapon, then defeat Gong himself).
After that, I opened up a new hunting ground, where I found a black star (although it didn’t appear to do anything), and then repeated the level so it gave me a new cap – reviving a blacksmith Patapon! Not that I can do the minigame he provides, as it’s clearly impossible.
Also impossible is the next mission – to rescue Meden from the Zigotons. I’ve tried it ten times, first not realising fire weapons actually kill Meden, then realising that you need the rain miracle or you fry, and finally just not being able to destroy the cart she’s in before the level ends. Grr!