Norrinir threw up a demo of changes we've brainstormed over the years and proposed multiple times.
https://vituscze.github.io/frostmage/ The ? button top right explains the vast majority. This was done to address scaling issues, proc munching, unused active talent options being non-competitive, and the entire "don't GS until BF proc" feeling awful. There's even some experimental spells that could replace the holes in the talent tree, such as where Splitting Ice is.
tl;dr: Frostburn, LW gets the GoSac treatment, Icicles are Frostbolt only, Flurry becomes charge based, BF restores half a charge, SI baseline and activates for 15s after a Blizzard, IV baseline 30s and increases Flurry recharge rate, Flurry launches Icicles when non-GS, Frostbolt gains bonus damage when Shattered which encourages doing the mini-combo properly, and as you stated refund/ignore FoF when throwing it into WC.
These would enforce the mini-combo, fixes scaling issues entirely, makes IV's strength worth being a 3m CD, fixes dead DPS talents (fuck you GI), proc munching, and the absolute ridiculous famine feeling when waiting for BF to proc for GS.