In the serialized version's extras meant to show their future, you can see Natalia is either always wearing these boots or sitting down and hardly moves. There's not a lot to go off yet, but Kamejiro is very deliberately teasing Natalia losing her legs again. Chapter 9's, when they're in bed, the boots are laid out right next to Natalia's bed for quick access. Chapter 8's, when they're in the bath, there's a towel covering Natalia's thighs where the scars are often drawn high enough to be. That one really takes on a different meaning when you know why Sara's checking for scars.
I like the mechanics of the boots, how they weaken her and the entire incident evens the relationship between Natalia and Sara. It's what necessitates them both caring for each other after Sara's breakdown instead of Natalia perfectly handling everything. So I hope this part remains the same. Though it's interesting Kamejiro changed the lore in the serialized version so children of spirits have infinite mana. I don't know how that's meant to work with the boots putting a limit on her mana.
Also I love that Natalia's reminiscing over how hard Sara practiced for her while popping off flowers like mad.