It looks like the PPM was corrected, but I looked into the stats as well. I'm not sure where you're seeing those stats, as I had to cludge debug output to grab the buff values in the log, but it does appear (maybe?) the the stats are lower in the sim that the tooltip says in-game. I didn't test the actual proc value (remote desktop isn't great for that), but assuming the in-game tooltip is correct, the 0.833422 multiplier in the Theorycraft Wiki can be removed now, as the values in game look to be 6276/2794 for Agi/Crit, which is exactly ItemBudget and ItemBudget * ItemRatingMultiplier, respectively (checked at 945).
Seeping Scourgewing I don't think I have the experience with DPS damage calculations to check it myself, so maybe one of the AMR team can check that one.
I'll take a pass through the rest of those Dec 5 trinket changes too, see what I can find. AMR often waits for live game data to verify these things before they put them in the sim, so it could be that something is different in the implementation/game data for these that they didn't get updated. It looks like Wowhead also doesn't have at least the Felhounds trink updated in its tooltip either, so that might be it since they are driven purely by extracted game data afaik.