I'm not a fan, of the sibset or the names.
Serenity has just always had a stripper vibe to me, not a virtue name vibe.
Coby just sounds so...lacking. It seems flighty and ditzy to me.
Sad thing is, I have seen girls starting to be named
Coby as well. And
Koby and Kobee, and Kobie, and Cobie, etc.