The cure supplied is not good.
Boot.bin starts with "KpGrd" 4B 70 47 72 64 good boot bin starts with 02 00 00 EA A2.
Region 5 looks OK and Region 43 looks OK (But I like the technique)
It looks like the file was made with makergn.exe
Something like.
makergn out.rgn 12 boot.bin 5 usreg_5.bin 43 usreg_43.bin