In Strasbourg, I put in my last name and my nickname (the first name that I go by on a daily basis, that appears on my credit cards, and that I use for my US Hermès account) but nothing came up. I then tried my last name and my legal first name as they appear on my passport and that worked.
In Amsterdam, neither method above worked. I then tried searching by only my last name and I was able to see the names (not purchase history, etc.) of other clients with the same last name as mine.
So ... you should be able to find both your account and your husband’s account by searching with last name only, if you have made a purchase in that country before. The account you are able to select may depend on the passport you are using for the VAT refund.