What to do with Valentine CEs?

I'll keep my favorites, and feeding the other to CEs.

All CEs you've ever owned (even after you burn them) can be viewed by going to My Room > Materials > Spirit Origin list.

Plus, next Valentine's event apparently makes it a lot easier to get CEs, giving them as ladder rewards, so assuming you finish the ladder, you'll get whatever you burn now back next year (except maybe Mash's, since I think hers is event-specific).

Personally, I'm going to save my 5 favorite ones (since they'll still give event bonuses next Valentine's) and use the rest for CE bombs the next time we have a super success bonus event.

I have been throwing them in my 2nd archive for CE for now. I got tons of room there.

Well, given the fact that you can view every CE you ever obtained in My Room, I think it's not a problem to use them as CE Bombs.
I mean, they don't even have any use in normal battles. They don't even have that much use in this specific event. The Gacha- and Event-Shop-CEs give the same or better bonus.

That's why, I will buy as much of them as I can. First for the cut scenes, second for the sake of having the CE. After that there's really no particular reason to keep them.

Buy all and saved the cut scene. And wait for the super/great Suc anr feed them to my lmb CE