The cbr125 and cbr250 engines share no major parts. The cbr125 engine is a traditional Honda single that has been around in some form for decades. The cbr250 engine was a ground up redesign. For the rest of the bike, although the 2nd-generation (2011+) cbr125 and 2012-2014 cbr250 have similar styling and share some parts (seats, gas tank, some fairing parts, aside from being painted differently) they're nothing at all alike under the skin. The frames are very different. Both made in Thailand though ... So is the Grom. So is the Ninja 250/300. I think the Yamaha R3 is, also. Check if the first letter of the VIN is "M".
As for the Kymco Quannon ... it looked similar but that's it. I know one person who bought one, and to say that it has not been very good, is an understatement. I know the sample size is small (one ... and I think I've only ever seen a couple of them) but based on that sample size, they're worse than Hyosung. I know he had two engine failures.
If BMW is getting engines built by Kymco under contract ... I sure hope BMW is keeping a watchful eye on them.