Maybe one of these and you’ll be able to use [name_m]Leo[/name_m] as a nickname?
[name_f][/name_f][name_m]Leonel[/name_m]
[name_f][/name_f][name_m]Leon[/name_m]
[name_f][/name_f][name_m]Leonardo[/name_m]
[name_f][/name_f][name_m]Leovanni[/name_m]
[name_f][/name_f][name_m]Leopold[/name_m]
[name_f][/name_f][name_m]Leandro[/name_m]
[name_f][/name_f]Rayleo / Raileo/ Raeleo
[name_f][/name_f]Raphileo / Rapheleo