The APIM gets the VIN info from the BCM, there is no VIN coded to an APIM.
So it appears that the APIM is working for the most part, but needs some settings corrected. The 2012 Ford Focus, built on the C1 platform (also known as the B-car platform), will need specific settings to communicate in the C1CMA platform. But since you say this APIM came from a 2017 Focus, this is probably not the issue.
FORScan will not be looking for Sync 3 in a 2012 Focus, so this could be an issue. You might try telling FORScan that the vehicle is a 2016/2017 Focus to be able to get to the APIM. If that works, you will be able to program the APIM, however, do not program anything else in that profile. This was a trick used for the early Sync 3 retrofits to earlier F series and such which worked. You can also contact FORScan support for assistance. Keep in mind you need a paid license of FORScan for support.