I've had ARPT status on two AF operated, DL marketed flights and it's never given me any problems.

According to some Travelport Galileo documentation (pdf), ARPT status is used when "the operating carrier has secured the [electronic ticket] coupon prior to the scheduled departure". Which would explain why ARPT status shows up for tickets involving flights on other airlines. IIRC, there are other threads on FT where people have had ARPT status codes and it's worked out.

I guess you could call to make sure your ticket looks okay, but it very well could be fine.