I think 帚 would be a good level 14 or 15 radical.
It is the right half of 帰 (15), 婦 (28) and 掃 (31). Currently, those all split that half of the character up into “Wolverine + Forehead + Towel”, and that’s kind of a convoluted image to use thrice.
“Broom” is the actual meaning of 帚, and a broom is a nicely pictoral thing to use in a mnemonic. Also, this radical assignment would make “掃 = Sweep = Fingers + Broom” really easy to remember. (“Sweeping is just using your fingers on a broom!”)
In fact, the character 帚 is really a pictograph of “a broom with bristles on top and tied handle on the bottom”, says Wiktionary. I can kinda see it if I squint :).
Right now level 14 only teaches six radicals. (Level 13 teaches seventeen of them.)
How would y’all feel about this?