It's a different board set regardless: CH256 vs CHA256B, 2 EPROMs vs P1 mask ROM.Its an OEM repair or modification.You can always tell by the eproms.
BB
one last bump
I bought this Waku Waku 7 and submitted board scans to mvs-scans.That board set is not on MVS scans, so consider sending hi-res pics of the front and backs of the PCBs. Or post here and I'll forward them.
I also have a Korean label cart but it has the same board set as pictured here: https://www.mvs-scans.com/index.php/Waku_Waku_7
Maybe run a CRC check on Unibios as well if you can.
Thanks and GLWTS.