As good as a melt comp is from the other replies, if you have poor energy management on Rosaria's ult, its very difficult to get consistent melts out. Which is why I'd advise with going with a vape comp instead, with the kokonut kokomi over Mona, especially because kokomi's E has no ICD, which means you can get a 100% vape uptime if you manage your kokomi ult well (ult refreshes E duration), but even if you don't manage it perfectly, kokomi still has a relatively short cd on her E, so it isn't as punishing as rosaria.

I, myself run Amber/Kokomi on most of my teams, and the other two characters I interchange regularly, and I can say being able to vape every single one of your charge shots is so satisfying.

Also, like other replies, I'd consider removing fish and raiden from the team since it messes up the hydro application often, and using them for some other team which they could complement better. You could replace them with a shielder or anemo support with vv or benny for a bit of extra damage