Is there any chance for releasing unencrypted resource (.rc) file with purpose of making translations by other people (users/volunteers)? Having an UI in native language could possibly motivate many users to buy the original version instead of clone (only supporting the old versions), just because the could easily understand all the messages and descriptions.
I do not have your interface, but I've seen your program and I believe I could try to prepare a Polish User Interface for it. Actually in Poland the clones are widely available at relatively low prices (less than 100€). I understand that - the cost of "fabricating" the clone is about 10-15€ (I actually have the interface schematic for it, it's not hard to find it and I believe it has been done by some Russian speaking guys, of course the .bin for uC is not so easily accessible), most buyers are the car owners not the car mechanics, and they won't be interested in paying more than equivalent of 3-4 "computer diagnostics" in Authorized Service (which is about 20-25€ per visit), on the other hand there are "garage mechanics" which often don't understand foreign languages. They often have even more expensive interfaces (often stand-alone, so surely legal/original), but the primary thing for them while buying a car diagnostic scanner is the fact of having a Polish interface.