I've been tried out that tileset compiler, awesome work, Ice M.A.N.!
Check the results:

(-), it was a lot of time to figure out the background color... The background color of the recolored main tileset bmp wasn't transparent, and I didn't knowed why. Of course I've been tried the hardest things you can imagine, and the solution was so simple: Just needed to replace the old palette, with the edited one's. Aw...
By the way, that an interesting thing, that JJ reads the enemies' & events' color values from the main tileset. That sometimes causes problems... And I don't know why they maded it like this, because with the bacground tiles it has 256*2 colors, and that's more than what can be stored in 8-bit. So JJ1 uses 16 bit, I guess. My question is to Toxic Bunny: Could it be possible, to make OpenJazz with stored event colors not in the tileset's palette? That should be open new ways... But I'm sure it's not the most important thing about OpenJazz right now.