I find most NECA figures stand better if I have one leg bent forward and one leg bent back, so maybe try adjusting them back and forth a bit until her feet have solid footing.

You could also consider buying a different stand. NECA makes some round peg stands for the feet, or you could go with something more like a figma action stand, I like these ones.

Yes! I got these a while back on Amazon and they're perfect imo. Good price for 8 of them, you just need a small screwdriver to put them together. They don't come with instructions but they're pretty easy to setup. I've used them for NECA, Star Wars Black Series, and McFarlane figures. So far no problems at all.

I order these from Amazon, they are pretty much the same, as what you post, and while assembly can be a little of a PITA sometimes, I find them quite sturdy.

Keep in mind 3 months ago I knew none of this existed, as I am back to collecting after literal decades away...lol

FINGERINSPIRE 8Pcs Action Figure Stand Assembly Action Figure Display Holder

I’m using these as alternatives to the obitsu stand. I can give a hearty recommendation; good stands and you get 8 for $20.