The problem was the lack of a proper .09 rom.
Here is the wrong one for this set:
ROM_LOAD16_WORD_SWAP( "vamu.09a", 0x300000, 0x80000, CRC(8dd55b24) SHA1(d99c2cbc4a9899a3d187201e6e730b7b8fb13d1d) )
Here is the right one:
ROM_LOAD16_WORD_SWAP( "vamu.09d", 0x300000, 0x80000, CRC(8b333a19) SHA1(5274510491433ac4a0ba3a0a120e95205d291ffe) )
Here's a patch from the wrong to the right one.