Some ideas:
Names that sound good in [name_f]English[/name_f] & Spanish:
[name_f]Claudia[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Camilla[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Annabel[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Sofia[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Julia[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Lucia[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Isobel[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Amalia[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Adelaide[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Leonor[/name_f] [name_f]Rhiannon[/name_f]
[name_f]Francesca[/name_f] [name_f]Rhiannon[/name_f]
I like [name_f]Paloma[/name_f] & [name_f]Estella[/name_f] too but they don’t flow super well to [name_f]Rhiannon[/name_f].
Names that are like [name_f]Rhiannon[/name_f]:
[name_f]Elowen[/name_f]
[name_f]Seren[/name_f]
[name_f]Susannah[/name_f]
[name_f]Romilly[/name_f]
Romela
[name_f]Ramona[/name_f]
[name_f]Aurelia[/name_f]
[name_f]Rowena[/name_f]
Brownwen
[name_f]Rosalind[/name_f]
[name_f]Gwendolen[/name_f]
[name_f]Liliana[/name_f]
[name_f]Sabrina[/name_f]
[name_f]Serafina[/name_f]
[name_f]Reyna[/name_f] / [name_f]Reina[/name_f]