Managed to make it to Boss Sakuya today.
Which is in particular an accomplishment, because my brother distracted me against Cirno, and I died on Icicle Fall because of it.
However, I had a brilliant Stage 3 and 4 run, and even Patchy went OK, with me captureing Wood Sign and Emerald Megalith. [The others I needed to bomb on, and I died due to mistiming her lasers once, and on Forest Blaze]