Microsoft actually fixed the problem - nobody from Haiku or any other BeOS project did. We don’t know what they did, THEY don’t know what they did…
BeOS also worked in the last non-Microsoft PPC version of VirtualPC but with extremely unreliable input - they’d fixed it by then.
You are right, this wasn’t the answer I hoped to get… I might have to contact MicroSoft and see what they say. Hopefully they can give some answers or at least a hint.