most of the games are possible to get in English. The program roms contains all the languages but the asic has the region set inside. From what I understand they needs to be decrypted and then patched and then encrypted again. I do have most of them in English, although all my carts are China, Taiwan, Japan region. I have promised the creator not to redistribute those roms. But it is indeed possible to do most of them. I wish I understood how to decrypt / encrypt roms myself, and i did try to understand it once upon a time but I never understood how to do it
even though the decryption keys are in name for many games I don't know how to write my own software to decrypt them.. even thought i could save the decrypted roms using mamae-debug but that didn't workout either. Would certainly love to learn it though!