Christians using Cohen/Kohen as a first name...hmmm....not too sure about that, I must say.
>> ...it feels part of a general trend toward co-opting Jewish traditions and then changing their meaning, or trying to tie it to Jesus.<<
Why Kohen is a top name in red states and Mira in blue ones – The Forward
https://forward.com/culture/707893/kohen-mira-baby-name-popularity/