I started FTX Central and let it update itself. Then I closed it and downloaded and installed the new libraries (from FTX site). Once that install was done, I started FTX Central again, and it started the migration process automatically before opening fully. Took a few minutes. Once done, I closed FTX Central again and ran the troubleshooter to check on the migration. It showed all files migrated successfully. Haven't had a chance to fly yet, but that is at least a good sign.
I had no problem with the original migration, however. But, since then, I've installed the new v3.3.5 version of P3D from scratch and most of the rest of my Orbx products, including AU and NZSI, which I knew caused some problems. So, I was a bit worried. It seems that all went well, however. I'll test it out in sim tomorrow.