I think [name_m]Leo[/name_m] needs a three or four syllable second, like [name_m]Christopher[/name_m] or [name_m]Sebastian[/name_m] (though I note that these aren’t short, so if you’re going short, I think it needs to have some heft and not have first vowel as an O, like [name_m]Ronan[/name_m] as assonance doesn’t sound good with [name_m]Leo[/name_m]).
I think [name_m]Julius[/name_m] with [name_m]Milo[/name_m] is too soft - with both having Ls in the middle and gentle i sounds. I would choose something short and strong, like [name_m]Ford[/name_m], [name_u]Cameron[/name_u], [name_m]Cormac[/name_m], [name_m]Xander[/name_m] to give some heft to [name_m]Julius[/name_m] (a name I really like).