I finally figured out what was zapping my Japanese input on Planner
pages: an overzealous extents+overlays zap in emacs-wiki. I read
through a lot of the font-locking code and I think I’m beginning to
understand how Emacs does it. Cool!
I’ve fixed it in emacs-wiki—dev and planner—dev. It seems to work
over here. Hope no one else has problems!