From your boy list, I think [name_m]Leo[/name_m], [name_m]Lucas[/name_m], & [name_m]Nicholas[/name_m] are the best choices for multicultural, multilingual appeal. [name_m]Leo[/name_m] is my favorite.
From your girl list, I think [name_f]Elena[/name_f], [name_f]Sophia[/name_f], & [name_f]Lydia[/name_f] work best. [name_f]Lydia[/name_f] is my favorite.
Other ideas:
[name_f]Adriana[/name_f]
[name_f]Anastasia[/name_f]
[name_f]Antonia[/name_f]
[name_f]Eva[/name_f]
[name_f]Luciana[/name_f]
[name_f]Nina[/name_f]
[name_f]Nora[/name_f]
[name_f]Selena[/name_f]
[name_f]Tatiana[/name_f]
[name_m]Alec[/name_m]
[name_m]David[/name_m]
[name_m]Joseph[/name_m]
[name_m]Leon[/name_m]
[name_m]Marco[/name_m]
[name_m]Thomas[/name_m]