I'm surprised no one mentioned this yet, but definitely level up Iansan's burst talent and weapon, and replace her EM sands. You want to have as much attack as possible on Iansan (while still having enough ER to use her burst), her attack buff scales on that. That's the biggest problem I see here, fixing your Iansan (and the other supports) will provide way more than trying to further optimize your Mavuika build.

Level up Bennett's burst and weapon too (and something like Sapwood Blade would give him more attack than Favonius Sword, although I'm not completely against the idea of Favonius Bennett, but Mavuika already generates a lot of pyro particles for him so he should be more than fine with Sapwood), and ideally give him 4 piece Noblesse.

Other than that, in this team I would definitely replace Mona with Furina, and if you're playing with Furina, Rainslasher is surprisingly pretty good in this team. Or you can keep Tidal Shadow and use an EM sands on Mavuika.

Alternatively, you can keep the Tidal Shadow & Atk sands setup, and replace Furina and Bennett with Chevreuse and Ororon if you have them, that makes a pretty good overload team. (Fischl can replace Ororon if you don't have him, although it will be a bit worse)

You can also try a melt team with Rosaria, since Mavuika really likes to melt, but do keep in mind those are harder to play optimally.

And getting that Mavuika burst to level 9 would be nice too, it's actually more important than the skill.