I would advise sticking with numerical pin numbers everywhere. There are many common packages, such as SOT-23, SC-70, SO-8 etc that are used for diodes, fets, bjts, ics. So the base footprint will use numerical pins to be compatible with everything. If you start using letters for pin designators then you have to create different footprints for diodes, fets, bjts etc, instead of having one common footprint.
So keep the pin designator numeric and use the pin name for A,K etc.