She have two problems.
First, she's designed for newer design of Challenge Quest (multiple Servant parties). If you saw Tales of Industry challenge quest where you better not kill Okuni, that exactly the kind of quest where she shines. Of course, that also means she had little contributions outside quest with that format.
Second, she's locked to Arts team. Her CDs are longer than OG Merlin; Quick and Buster are not into giving their CD reduction to support. So no "You have two Arts card? Good!" like Merlin helping Servants with at least two Buster cards.
TLDR, she suffered from designed for specific kind of fight and belongs to card type already full of supports.
If you actively tackle CQ with Arts party, she's good.
If not, the best she could do is helping Arash and Gong.