Undercurl looks like underline

[supersurviveur]

Hi ! I love this font, but undercurl looks bad:

With other font :

I get a working undercurl by editing font ascend or descend in the monocraft.py file, but all chars are moved by 1-2 pixels up and become ugly and less readable. How can i get better undercurl without moving chars ?
Is there a way to increase line height too ?

It seems that it comes from alacritty, but I'm not sure, and I don't know how to fix it.

[supersurviveur]

I finally succeeded to increase line height.
here is the code https://github.com/supersurviveur/Monocraft/tree/increase-lineheight