It's probably hard coded into the window and door PIO's.
The doors and windows themselves get classed, but nobody thought to read the file for secondary items.
Oops, I'll take that back, the "style-X" classes do...for door and window PIO's.
But other PIO's don't, so you wind up with "style-custom1" and "style-1" in the same drawing.
There is a parameter of the PIO for the tag, but nothing for the ceiling.
personally, I don't see much to be gained from changing "-" in layer names to "_" even if you should be able to do it.