Aye, Invader was originally set from 2-4, or so said the numbers in the file there; I had the other floor 3-4 bosses set a bit differently from no apparent reason, so I set them all to 2-4 to see what'd happen. The game wouldn't run. Well, it'd run, but it wouldn't stop "cackling with glee" or whatever it does when it cant find bosses.
Including Invader, they're now all set from 2-5. Seems to be going well on my current run.
The bloody floor index thing is confusing.