I've always loved both of these characters, especially no-nonsense post-war Neville. And as a former barmaid, I've always had a bit of a soft spot for Rosemerta. I've never bothered/had an opportunity to write them before, so I'm especially glad to hear they came across as believable.
And yes, it always is the quiet ones, isn't it? ;) I have no idea why more fanficcers don't take advantage of that fact.