Congrats. She looks nice. I may try her too.
For the event swimsuit 6*, I think you need both. And maybe Alstroemeria Formal Dress and RRose Swimsuit. But I'm not sure counter is still worth it. Counter damages don't deal enough damages and worth the huge HP sacrifice in the current meta. Old Counter are too outclassed and you need to pack the newest ones to make something. I may be totally wrong though (I wish I am). I can't test it.