Lin's art is genuinely great- I've rarely seen anyone who's able to so perfectly integrate the aesthetic of the original designs with more realistic facial features and elements.
Oh yes, more navel licking.
And as for why Carmilla x Nozomi, it's probably commissioned from that one fanfic writer (on Ao3 or something) who's into navels and has Carmilla x Nozomi as one of their fav pairings.