There has been a bit of work done recently with the bootleg version(s) of Bubble Bobble (Bobble Bobble).
The story can be found over on the Arcade Otaku forums, https://forum.arcadeotaku.com/viewtopic.php?f=26&t=5154
Basically the joaoljr has added the code found in the MCU of the original pcb into the ROMs of the bootleg and it has resulted in what is almost, if not completely perfect Bubble Bobble. Title screen and all is restored.
I did take a picture but it can out horrible so I wont add it but it does work.
Thanks to joaoljr for doing this patch.