Whelp... I didn't realize this was a time-limited thing either and now I have like 600 worthless tomes lol. There's literally no reason why these tomes should not be able to be spent after the event has ended like past events, and it's honestly pretty annoying that SE randomly switched up how these things work from from other recent Moogle tomestone events, which allow you to spend your tomes after the event is over.

Just because you got double tomes from this event doesn't at all justify disallowing players to spend them shortly after the event has ended. This one really baffles me.