Thank you for making this gem available!
I wrote a PM with some answers and a description of the current state.
The Rainbow driver should be restructured next, best before the 100-A ROMs are available.
For now, a recompile cycle is necessary (since all assumptions concerning the 100-A are kept in hand-crafted precompiler macros, which is kind of safe but very ugly).
Hint: i could use some help
Last time i tried to use MACHINE_CONFIG_FRAGMENT(.. ) for alternate machine configurations around MAME 0.160, it caused problems after the second machine reset.
Additionally i seemed unable to cover subtle differences in port logic with this approach...