Two of the best dot matrix printers of that era were the Epson MX-80 and MX-100. They supported Katakana out of the box. https://epson.com/faq/SPT_M80~... Yes, these were 9 pin printers. I'm guessing Epson did not support simplified Chinese due to low market demand at the time.

"Gruber calculates that MacHeist will record double, if not triple, the profits of all ten participating developers combined."
 

Where there's a good margin, competition will follow.