Morten and Peter managed to dump the internal rom of Dodonpachi Daioujou Tamashii, a Chinese release of Dodonpachi Daioujou on PGM2 hardware that offers an ‘easy’ mode.
extracting this one was more difficult (I’ll update this post / do a new post explaining why later)
unfortunately for now it also appears to expose some more bugs in the MAME ARM core, these are being looked into, but basically a lot of the sprites end up with a value of ‘0’ for palette selection instead of the correct value causing them to be rendered with incorrect colours. There are no additional video attributes being set so it seems logical to conclude it’s a CPU emulation problem at this stage.