Oh thanks so much for your replies!
A few of you mentioned [name_f]Soleil[/name_f] as an alternative for [name_m]Sol[/name_m]. Because we live in a [name_m]French[/name_m]-speaking community, I think it’s connotated differently here, like extra-extra-hippie. ^^
So many beautiful suggestions - I’m surprised how many of you actually found names that were on our longer list, you “read” our style very well!
@babies123456
[name_f]Cecily[/name_f] doesn’t work in [name_m]French[/name_m] and Spanish as much but I’ve always thought it was lovely.
[name_f]Nova[/name_f] would be on our list but really doesn’t work with the last name, sadly!
@minkling
[name_f]Greta[/name_f] is striking, I’ve thought about it. It has a similar feel to [name_f]Frida[/name_f] for me. I would consider it if it wasn’t for the [name_m]French[/name_m] pronunciation.
[name_f]Cleo[/name_f] I really like too, it was on an early list of mine. I think what’s not quite right for me is that it sounds like a lot of popular names at the moment, and I guess I like a bit of an offbeat choice.
@danakatherine
[name_f]Agata[/name_f] I love. It has come in and out of our list in the last weeks; my partner is not sure of the “gata” bit (cat in Spanish). Maybe I should insist! hehe
[name_u]Indigo[/name_u] I’ve been fascinated with for a while, but I can’t quite get to the place of considering it, like it’s not quite an actual, possible name in my head yet. It also doesn’t sound as great in [name_m]French[/name_m].
@wilkie8709
[name_f]Aurora[/name_f] was on our list until recently - the [name_m]French[/name_m] pronunciation once again dissuaded us. Absolutely gorgeous name.
[name_f]Serafina[/name_f] comes to my mind once in a while, I really like it. But my name is [name_f]Sarah[/name_f], so it feels a bit too close.
[name_f]Esme[/name_f] I adore, it was on my list before my partner got to it 
[name_f]Lux[/name_f] not so much but it reminds me of [name_f]Luz[/name_f] I really like. Doesn’t work in [name_m]French[/name_m] unfortunately.
[name_f]Rosalind[/name_f] was on my list also. Here the problem is the last name that starts in “N-”, the “nd-N” doesn’t flow.
[name_f]Leona[/name_f] is very pretty, I’ll bring it up to my partner.
@michellem
Thank you for taking the time to review every idea - it helps a lot. [name_f]Lorelei[/name_f] is definitely pronounceable in [name_m]French[/name_m], it’s just that [name_m]French[/name_m] 'R’s are much “dryer” or “stiffer”, I’m not sure how to describe it, and so names tend to lose some of their charm in translation. In the case of [name_f]Lorelei[/name_f], though, apparently not enough for me to get it out of my head!
From your suggestions I quite like [name_f]Beatriz[/name_f], the subtle link of the 'Z’s between sisters is appealing to me. It would constantly need to be spelled here though, people would hear and write Béatrice automatically.
[name_f]Freya[/name_f] is very pretty and strong, not ideal in [name_m]French[/name_m] unfortunately because of sound-alike words.
[name_f]Isolde[/name_f] is beautiful, but not great in [name_m]French[/name_m] either unfortunately (“en solde” is [name_m]French[/name_m] for something being “discounted”).
@lunette
[name_f]Agatha[/name_f] (spelled [name_f]Agata[/name_f]) has come in and out of our list in the last weeks. I really like it, but my partner is not sure of the “gata” bit (cat in Spanish). I would go for the Spanish-friendly spelling for the sake of harmony with the last name, but it does mean the English pronunciation changes, and I miss the soft “th” a little.
[name_f]Isolde[/name_f] is beautiful, but not great in [name_m]French[/name_m] unfortunately (“en solde” is [name_m]French[/name_m] for something being “discounted”).
@books_and_tea
Thank you! It seems [name_f]Frida[/name_f] and [name_f]Juno[/name_f] are distinct favorites on this thread, interesting!