It's liking trying to get a TS55 req to be square at 0 degrees. There is adjustments for this, but there is no real way to hold the whole assembly properly while you adjust and tighten (awful design)
Get a Digital Bevel Box Gauge , calibrate it to your (flat) worktable, set a rail so that the side with the splinter guard strip overhangs, set the saw on the rail and clamp it down (gently!) - now you have your hands free to remove the side cover, attach your Bevel Box using the magnetic side to the blade (onto the flat inner part, sparing the teeth).
Perpared like this you should be able to perfectly calibrate your TS using the information and procedures in
http://festoolownersgroup.com/festool-how-to/how-to-set-ts55-bevel-to-0/ (and linked topics).
similar for the offset, how does one gauge this and get it set before/while locking it all down. Festool probably has a factor fixture for this that they set the tool in loose, clamp and then tighten the screws.
Put the rail to adjust the saw to onto a table so it overhangs on both ends, then you can slide the saws base a bit over the rails end to access the screws you have to access for the procedure (without having to lift the saw from the rail), not loosening them fully (so you can carefully tap the top into alignment) helps.
See page 22 in
https://service.festoolusa.com/media/pdf/Festool-TS55REQ-Supplemental-Manual.pdfIn general I agree with your idea that everything should be perfect from the start, but we don't live in a perfect world and the 3 years
service all included will solve out of the box imperfections...