Wow, this is some super old bug, from 2000 at least, I must confess I never played soldam (japenese game so...).
You read japenese ?
So this is some very old code from Antiriad, I made some tests and found your disappeared layer, it's because it's usually drawn as 16x16 sprites but for this screen specifically, it's drawn with 8x8 sprites, and this was unexpected, the 8x8 sprites are not available !
I'll need to read some more code to see how/if the 8x8 sprites can be generated, it's probably not too complicated, but it's some totally unknown territory here... !
Thanks for the nice things too by the way, and nice to see another arch user !