My observations after a first glance:
First, the AC15 template does not contain all of the Pen Sets listed.
Second, it seems odd that the "Architectural 100" set is listed as the default.
Third, the AC15 library doesn't seem to use the "Architectural 100" set, in which case I'd stay away from it until it does.
MacBook Pro Apple M2 Max, 96 GB of RAM
AC27 US (5003) on Mac OS Ventura 13.6.2
Started on AC4.0 in 91/92/93; full-time user since AC8.1 in 2004