From what I can see, a Mace Toss up charge helps with setting up for some of her combos by lifting them into the air. You can get a few nice combos in the 30-35's if you do that. Plus it feels sick since not many Hawkgirls do that.
Mmm. But I suppose better training and muscle memory is all I need as you said to get it down.
Mm, her mixups? She basically has two lows in her entire moveset. B22(3) and D3. And D3 isn't very practical imo. But yeah, bettering our mixups would be nice. But her B22 and B23 is generally what I use to start corner combos as it's a decent 50/50. But maybe like you said, perhaps we do need to use more D2 cancelling.
Although I prefer to use her zoning and movement abilities like WE3, iaD3, MB down MT from the air during corners and 22U3 (which is safe and flips you to the other side if they block it) for constant ambiguous cross-ups to play with.