Maple Swimsuit is far from the best attacker but why not. There is not only stupildy hard stuff anyway. I'm sure she can be good somewhere.
Your teams options seems not that bad. Sigilaria+Adlay would help Maple for sure. Almost anything can be good with Adlay anyway.
RRose swimsuit is nice but HP drain will be peanuts without Adlay. Enemies hit so hard. Looks like Nipplewort Dog bring a bit more power and usefullness but once again, you will certainly need Adlay to survive long enough to stack five Crit buff.
Another girl I really like to use (if you didn't miss her reprint. She is an event 6*) is Spring Star Parallel Academy. I think she could kinda works with RRose Swimsuit before you can get Adlay. Or with Nipplewort too.

For intercept I used the exact same team and had the exact same problem with Juneberry. I replaced Purslane and Black Locust Bride by Usagigiku & Usagigiku swimsuit. The team became almost unkillable but lacks a lot of power. Expect >30min long fights.
Intercept works well on Adlay and Zinnia map but not on the others. They can be good for Honeysuckle if you have something to kill her after she goes below 30% HP (or 10?).