Or at least make it so, that used seal scrolls count for next time these treasues are on. For example first time Time-Limited Edo Jinch treasure is on player uses half of seals needed for that Edo Jinch, but runs out of seals. Next time that treasure is on that player spends same amount of seals (second half needed). They should be albe to get Edo Jinch that time, instead of having all needed seals on 1 time.

Although I think making these treasures permanent might be easier thing to do.