We played with some, but none stuck.
A big goal was being short and easily pronounced, including by non-native English speakers, in a recognizable way from reading the text. That made the overwhelming majority of "fun" spellings not work well.
On one hand, I feel like we're just not as good at naming as Rust and Zig. Both of those names are :chefskiss:
On the other hand, Carbon does have a bunch of awesome puns waiting for us... So we've got that going for us. =D