I kinda like characters like Celt. He owes Elma and Luce his life, but it kinda feels realistic that he's not going out of his way to risk his neck for them, but will help them with stuff like this.
I find it more jarring when manga has characters that will just trip over themselves to help the MC for much less.
Celt isn't really a selfish guy IMO even back during the introduction, when Elma and Luce hasn't really proven themselves at the time. Now he knows Elma's really damn smart and he can stand to benefit to getting along with Elma. It's more grounded that way instead of characters being insanely selfless.