I think [name_m]Zigmund[/name_m], [name_m]Laszlo[/name_m], and [name_m]Osric[/name_m] work really well with your girl names. All are established, quirky, and slightly clunky with the possibility of a fun nickname. I also really like [name_m]Caspian[/name_m] and [name_m]Casimir[/name_m], but I think they may be a bit too close to [name_f]Callista[/name_f].
Other suggestions:
[name_m]Amos[/name_m]
[name_m]Lysander[/name_m] (“Sandy”)
[name_m]Emrys[/name_m]
[name_m]Magnus[/name_m] (“Gus”)
[name_m]Arlo[/name_m]
[name_m]Sebastian[/name_m] / [name_m]Basil[/name_m] (“Baz”)
[name_m]Hollis[/name_m]
[name_m]Leander[/name_m] (“Leo”)
[name_m]Atlas[/name_m]
[name_m]Otis[/name_m]
[name_m]Edmund[/name_m] (“Ned”)
[name_m]Florian[/name_m] (“Finn”)
[name_m]August[/name_m] (“Gus”)
[name_m]Adair[/name_m]
[name_m]Aurelius[/name_m]
[name_m]Cosmo[/name_m]
[name_m]Francis[/name_m] (“Finn” / “Frankie”)
[name_m]Harris[/name_m]
[name_m]Lev[/name_m]
[name_m]Remus[/name_m]
[name_m]Eamon[/name_m]
[name_m]Cypress[/name_m] (“Cy”)
[name_m]Killian[/name_m]
[name_m]Evander[/name_m] (“Van”)
[name_m]Forest[/name_m]
[name_m]Theodore[/name_m] (“Theo”)
[name_m]Inigo[/name_m]
[name_m]Atticus[/name_m] (“Kit”)
[name_m]Silas[/name_m] (“Si”)
[name_m]Peregrine[/name_m] (“Perry” / “Pippin”)
[name_m]Ephraim[/name_m]
[name_m]Solomon[/name_m] (“Sol” / “Sonny”)
[name_m]Ewan[/name_m]
[name_m]Caius[/name_m] / [name_m]Mordecai[/name_m] (“Cai”)
[name_m]Lorcan[/name_m]
[name_m]Oberon[/name_m] (“Obi” / “Bear”)
[name_m]Jasper[/name_m]
[name_m]Orion[/name_m] (“Ori”)
[name_m]Orson[/name_m] (“Ori” / “Sonny”)
[name_m]Hawthorne[/name_m]
[name_m]Declan[/name_m]
[name_m]Archer[/name_m]
[name_m]Cato[/name_m]
[name_m]Lionel[/name_m] (“Lio”)
[name_m]Ari[/name_m]
[name_m]Asa[/name_m]
[name_m]Amias[/name_m]
[name_m]Kieran[/name_m]
[name_m]Osmond[/name_m] / [name_m]Oswald[/name_m] / [name_m]Oscar[/name_m] / [name_m]Oswin[/name_m] (“Ozzy”)
[name_m]Lazarus[/name_m] (“Russ”)
[name_m]Lucian[/name_m] / [name_m]Lucius[/name_m] (“Luc”)
[name_m]Isidore[/name_m] (“Izzy” / “Sid”)
[name_m]Alistair[/name_m]
[name_m]Owen[/name_m]
[name_m]Lachlan[/name_m]
[name_m]Everest[/name_m] / [name_m]Everett[/name_m]
[name_m]River[/name_m]
[name_m]Stellan[/name_m]
[name_m]Jude[/name_m]