1. Avoid PvP trinket usage report
To reproduce this bug simply equip your PvP trinket in the waiting room <10s before the match starts. After that the API will not fire on event and report trinket used during the match to blizzard default arena frames or third party addons.
2. Combat bug
Classes that have an AoE buff, such as priest "Prayer of Shadow", can cast the spell when their partner gets in combat from 40+ yards. This will also put the player in combat. There is a range limit, but it seems to be 250 yards if not more instead of 40 yards.