If you’re after legitimate BIOS then the 21576H Japan BIOS is very compatible on Naomi 1 and similarly 23605C for Naomi 2.
If you (or anyone in Australia) need a hand getting them burnt, drop me a PM and I’ll get them done for you, just send me some 27C160 chips and pay for postage back.
Yep. No issues whatsoever. Have all the DIPs off and just run it in Japanese for the most part. I have to power down to load Naomi games after AW, but that’s a known issue.
Edit: Read the thread you posted, two remedies that spring to mind, perhaps try alternate versions/downloads of the AW2Naomi games or wiping your SD and starting fresh. Also, maybe your multi BIOS was burnt incorrectly or on a chip that was a bit flakey or too slow?
I suggest fresh burns of the multi BIOS as well as the legitimate ones to eliminate the cause of your issues and troubleshoot.