Thanks for you kind comment! :D and yes, I'm searching for the cause that isn't working on TurboR...
It seems that the ROM version has been created with a DSK conversion tool. Maybe the dsk2rom tool has a bug?
I think I've found what's causing the issue. Both flash loading tools and OpenMSX are reporting the ROM as using a Konami megaROM mapper, what is wrong.
It works fine if you manually set the mapper type to ASCII/8KB.
By the way, I suggest you to crop the ROM files to an actual ROM size (usually power of two numbers, 1048576 would be fine) and pad the empty area with 0xFF. A real ROM chip cannot have a size such as '753664' bytes. It might cause some issues on some emulators/flash cartridges/ROM launching tools.