If [name_f]Gwen[/name_f] is your absolute favourite girls’ name in the world, I’d go for it. I tend to go with using the names you love the most even if it doesn’t make the perfect sibset, within reason. (Not like, [name_m]Daniel[/name_m] and [name_f]Danielle[/name_f].) If there are other names you like though and [name_f]Gwen[/name_f] is just one of the options you’re considering, I’d pick something else since they do look quite similar. (Not just that they both end in “wen”, but capital O and G are a similar shape.)
I wouldn’t use it, but [name_u]Owen[/name_u] is not name I usually like.
Go for it if you love it, don’t go for it if you can find similar names.
TBH, even if you choose to name kids [name_u]Owen[/name_u] and [name_f]Gwen[/name_f], it would be yours decision (negative comments can never be avoided) and kids would still be as happy as any other children. Those are names, nothing overly important in life, although sometimes we, adults, make fuss about these things.
Similar names
[name_f]Greta[/name_f]
[name_f]Bridget[/name_f]
[name_f]Megan[/name_f]
[name_f]Rosalie[/name_f]
[name_f]Giselle[/name_f]
[name_f]Cecily[/name_f]
Gwenllian - or [name_f]Gwendolen[/name_f], if unusual flair don’t attract you
[name_f]Wendy[/name_f] (nn for [name_f]Gwendolyn[/name_f], I believe, but it’s standalone name)
[name_f]Maud[/name_f]
[name_f]Isabella[/name_f]
[name_f]Juliet[/name_f]
[name_f]Sabrina[/name_f]
[name_f]Cordelia[/name_f]
[name_f]Jasmine[/name_f]
[name_f]Aurora[/name_f]
[name_f]Lucy[/name_f]
[name_f]Mary[/name_f]
[name_f]Lucia[/name_f]
[name_f]Mabel[/name_f]
I listed some names I like, since I’m also fan of [name_f]Gwen[/name_f], but also some other that are similar in style with [name_f]Gwen[/name_f].
I really don’t see any problem with two different names that aren’t pronounced similarly. If the visual of it really is a nagging issue for you, would you consider [name_u]Owen[/name_u] and [name_u]Gwyn[/name_u]? [name_u]Owen[/name_u] and [name_u]Wren[/name_u]? [name_u]Owen[/name_u] and [name_f]Belen[/name_f]? [name_u]Owen[/name_u] and [name_u]Quinn[/name_u]? You’ll have a stunning sibset either way!