"Scartlet Twins"
I highly doubt Cryska and Inia are the pair of twins...
So I guess Cryska has a twin sister, who's not Inia. I might be possible Inia also has a twin sister. And the for of them are tandem pilots for 2 similar TSFs. Both statements are a large stretch, compared to the simple idea that Inia probably isn't Cryska's twin sister.

No regarding the progression of the show:
Who care mastering a blade, when I has a bigger gun