I got an update from PSA on the issue with their PA-10 lower and trigger compatibility. I asked if are working on a long term fix like coming out with a new lower that will not require any machining on aftermarket triggers, and this was their response:

"We are working to correct this issue, and a new PA-10 lower receiver is in the works.

Thank you,

Customer Service
Palmetto State Armory
(803) 724-6950
Info@palmettostatearmory.com"

So that is good news. Looks like there will be a completely new lower that fixes the issue.