Since you asked, I like [name_u]Cleo[/name_u] a little better than [name_f]Leora[/name_f]. Is [name_f]Mathilde[/name_f] an honor name, or are you looking for suggestions for middles, too?
To me, [name_f]Mila[/name_f] & [name_f]Leora[/name_f] are the more mature, international pair and [name_f]Mila[/name_f] & [name_u]Cleo[/name_u] are hip and artsy.
I would go for [name_f]Mila[/name_f] and [name_f]Leora[/name_f]. (How are you pronouncing [name_f]Mila[/name_f] btw?)
If you like the [name_u]Cleo[/name_u] sound and to mix it up so the M of [name_f]Mila[/name_f] isn’t repeated, you could use [name_f]Leora[/name_f] [name_u]Cleo[/name_u]. I was going to say [name_f]Clothilde[/name_f] for the Cl sound but it’s not the best flow with [name_f]Leora[/name_f]. [name_u]Or[/name_u] to go for a name on par with [name_f]Sophie[/name_f], maybe [name_f]Leora[/name_f] [name_f]Chloe[/name_f], [name_f]Leora[/name_f] [name_f]Daphne[/name_f], [name_f]Leora[/name_f] [name_f]Delphine[/name_f], [name_f]Leora[/name_f] [name_f]Poppy[/name_f], [name_f]Leora[/name_f] [name_u]Camille[/name_u], [name_f]Leora[/name_f] [name_f]Tess[/name_f], [name_f]Leora[/name_f] [name_f]Maisie[/name_f]. [name_f]Leora[/name_f] Zoe).