OK, it was confirmed that the problem comes from the wrong description in the Lionel catalogs and web site. The actual length of these turnouts is 11 3/8".
The updated Lionel-O-Fastrack library for SCARM is ready and published - you can get and install it from the links in the bottom of the same
Potential Problems With Lionel O FasTrack O31 switches blog post. The library will be also included in the next version of the program.
Mixy