I have a return trip to take, so I updated my FF program to AF and will report back.
Oh as a data point, I made my booking via an OTA. The OTA doesn't give me an option to add an FF program, but I could just do so on Saudia's website.
Hopefully it won't make a difference for API or whatever but I noticed that if one edits pax info (such as for FFP), the SV website appears to subtract a day from date of birth each time (much as editing flight search subtracts a day).