Just published an update (v2.2.0) with better support for original Gameboy. I’ve also included a .gb and .gbc versions of the rom in this update (both versions are identical, but this caters for those emulators that pick the support based on the file extension)
I’m afraid this is down to your emulator/set up. Both roms will play properly on original hardware and in emulators where they’re set to DMG mode. But yes the colour data is included in the rom and some emulators will need to be configured to ignore it. I’ve no plans to publish a build explicitly without it.