Here is a quick rundown of the numbers I pulled off the log when I killed a mob:
From L2 message log:
5499 xp (bonus 4277)
+611 player commendation bonus
base xp of mob: 1222 = (5499 - 4277)
base x1.5 (rec) = 1833
x3 (vit4) = 5499
base x 0.5 = 611 (pc commednation bonus)
From this it's clear neither vit or rec bonus is being applied to the event bonus, resulting in a very small increase to the xp.
"During the Player Commendation Event, everyone gets a 50% XP bonus, making the XP rate 1.5. This stacks with all Vitality-related items, but experience points gained from quests are not affected."
FYI, the phrasing of the double exp week was identical, and vit/rec DID apply in those cases:
All experience points and skill points gained from hunting monsters are doubled. This stacks with all Vitality-related items, but experience points gained from quests are not doubled.
----> "This stacks with all Vitality-related items" <-----