I’m an Aussie in Oz so I can’t help you with the Clair-uh, I’ve only hear Americans here say Clah-rah (bc they’re referring to Australian kids who have that pronunciation). Wondering if by time you get home, your daughter will be old enough to say “it’s Clah-rah” and all your family will be used to saying it the Brit-Oz way?
Re Willa, my family weren’t sold right away because they hadn’t heard of it - she’s 10 next month and I didn’t know any Willas. My mum (and others) knew of the American author, Willa Cather, but it was still not a name they were comfortable with. But I still get positive comments on her name on first intro. Sure, probably a third of the time people ask if it’s Willow, but that’s getting less common. No problems with spelling. We call her Will, Lily, Willabee & a bunch of other names. Definitely a handful of other names I like as much but remain happy with my choice - love the blend of soft and dreamy as well as a tad discordant and bolshy. I met a 20 year old Willa the other day and it still works, whereas (unlike PP) I see Maisie as the youngest-sounding of your names.
Hope this helps!