klegeni fu'ivla

x1 has x2 (ka) as their gender; x1 identifies as gender x2.

From -kle- (< klesi) and the ending of trangeni, singeni. The -geni ending is ultimately from Latin genus and its descendants (cf. English gender).

In notes:

jenri
x1 is the gender (social, not biological sex) of x2.
nongeni
x1 is agender. x1's gender identity is not identifying with any gender.
sekse
x1 is the biological sex (male, female, or otherwise) of x2.