Please take a look at what Temp Relics are offered in the events store and carefully compare them to what shows up in players' main relic screens vs players' battle screens when testing.
The relics do not always match up where they should. For example my 'main" relic screen shows that I currently have temp "Arena offense" relics which I never actually bought. Stay with me here -- this is where it gets weird. I DID get Gauntlet Temp relics on Monday 5/20. They first showed up a week prior and I purposely waited until the last day they were available because I wanted them to "carry over" into the next gauntlet because I did not have time to use them that cycle.
My "main" relic screen shows there are 4 days left for my Arena Offense boost (which was sold as a Gauntlet boost that I apparently got so late that it broke something) and I have yet to play much Gauntlet but that's beside the point.
My point is that my main relic screen says I have "Arena Offense" temp relics while my TOONS do not show ANY boost in the arena but they do in Gauntlet.
Additionally I do not see the Arena Temp relics available in my store as others do (I assume because I still have the Gauntlet Relics displaying as arena relics) and that one cannot have both. If one CAN have both then the issue is that I don't have the option to buy actual arena boost temp relics (not that I would anyway at this point).
Damn I use a lot of parenthesis.
So bottom line is that while these temp relics may or may not do much, they are not showing up where they should and are also showing up incorrectly labeled in other areas. My suggestion is to take a look and see about tightening that up. For the tiny fraction of players who would ever even notice.
Cheers