[name_u]Dominik[/name_u] is great! [name_u]Niko[/name_u] is a great, strong name, and [name_u]Mika[/name_u] is great fun (and very handsome) but [name_u]Nik[/name_u] and [name_m]Dom[/name_m] could be other options that your SO might like too. I think Lucjan would throw people a bit- how is it pronounced? I am guessing LOOS-yen or loos-YEN? Sorry, I don’t know how accurate my information is as to whether or not these names are used in Poland, but hopefully these suggestions are okay.
These would translate well (in my opinion) Polish / English:
[name_m]Makary[/name_m] (Mak / [name_m]Mack[/name_m] or [name_m]Kary[/name_m]), [name_m]Oskar[/name_m], [name_m]Nikolai[/name_m], [name_m]Adrian[/name_m], [name_m]Leon[/name_m], [name_m]Damian[/name_m], [name_m]Daniel[/name_m], [name_u]Florian[/name_u], [name_m]Robert[/name_m], [name_m]Marek[/name_m], [name_m]Anzelm[/name_m], [name_m]Casimir[/name_m], [name_m]Franio[/name_m], [name_m]Izak[/name_m], [name_m]Idzi[/name_m], [name_m]Eryk[/name_m], [name_m]Henryk[/name_m], [name_m]Konrad[/name_m], [name_m]Koby[/name_m], [name_m]Maksym[/name_m], [name_m]Rye[/name_m], [name_m]Symon[/name_m], [name_m]Patryk[/name_m], [name_m]Teos[/name_m], [name_m]Salvator[/name_m], [name_m]Marcel[/name_m], [name_m]Aleksy[/name_m], [name_m]Albin[/name_m], [name_m]Aleksandr[/name_m], [name_m]Aron[/name_m], Augustyn, [name_m]Aurelius[/name_m], [name_m]Aurelio[/name_m], Brunon, [name_m]Cyprian[/name_m], Emmilian, [name_m]Feliks[/name_m], Holleb, [name_m]Jack[/name_m], [name_m]Kelby[/name_m], [name_u]Kolby[/name_u], [name_m]Pawl[/name_m], [name_m]Stefan[/name_m], [name_m]Teodor[/name_m], [name_m]Tolek[/name_m].