This one is tricky.

Though Felicia has more interactions with Tsuruno than anyone else, I think their personalities would mix, but in a rocky sorta way.

Now it wouldn't be toxic, I feel like Felicia would get extremely riled up and Sana would be there to stop her from hurting herself, and Felicia would be there to help Sana get in the right spirit to keep trying to improve in a fight.

But I'd be rocky because I'm sure Felicia would be to tough and prideful to say anything about her feelings for Sana, and Sana would be to shy.

Besides, Sana can barely take care of herself and Felicia's to immature for romance at the moment. I'd be interesting, but probably wouldn't be the main part of a story.

So yes, I like it, but because of specific reasons I think they're to young and not ready to date quite yet.