Considering the mention of a party being recommended to be at least level 60 before fighting the Dark Lord, plus some of the things that happen on Book 3 without spoiling anything, the original boss-version Yumiella never was close to the level cap, so my guess would be:
Current anime party close to but not up to level 60
Dark Lord at about level 65
Game Yumiella at about level 70
So yeah, Our Yumiella should be able to easily defeat the Dark Lord at this point.
Now, entering Book 3 heavy Spoiler territory (don’t look if you haven’t read it) to further justify these numbers:
spoilerYumiella 2 was the only Boss Yumiella survivor on the multiverse branch beating the Hero party because she used our Yumiella leveling techniques, so she was much stronger than normal boss Yumiella, but was still weaker than OUR Yumiella, so she never broke the level cap. That leaves my estimate of her level on Book 3 at somewhere above level 70 up to 80, maybe something in the lower 80s, but lower than level 90.