Cantarell has served us well, but we’ve been wondering if it would be more beneficial to default to a more modern and well-maintained typeface
Eh. I don’t feel Cantarell “dated” or “not modern”. I don’t even use GNOME anymore but I reckon Cantarell is actually a great font, it’s legible and has character. It’s almost like you can tell it’s about GNOME when you see Cantarell somewhere. If I were them I’d invest into giving it more weights (I’d really like it if it had a lighter version), variations and extending it. They have the power and resources to do so.
imho they’re trying to solve a problem that doesn’t even exist. Inter’s default is a poor choice, as some of you have already noted here.