My version of scph5500.bin has the correct MD5 checksum of 8dd7d5296a650fac7319bce665a6a53c and the CRC32 checksom of ff3eeb8c
I think it might be a filename issue. I'll experiment with added a dash in it like scph-5500.bin
Edit:
I've tried many filename cases but non seam to work when trying to play Japanese games but I did find out that it really doesn't matter what case the BIOS files are to play the US games and also worked with just about every BIOS version (US games playing with any J, E and U BIOS files 10x, 100x, 300x, 350x, 500x, 550x, 700x and 750x). Some US games will even play without a BIOS file but it gives a quick message stating "no BIOS found, expect bugs!"
I'm testing with 2 Japanese games: Captian Commando and Nekketsu Oyako. Maybe neither one of these work with the emulator.
Does anyone out there have any Japanese games working and which one(s) did you get working?