I studied Latin in Newcastle and definitely heard "Novocastrian", but I'm certainly an outlier. I can't imagine any Geordie you're going to meet in St James' Park is likely to use the term.
Mancunian, Glaswegian, Geordie, Liverpudlian and Scouser, and Bajan are all commonly used. I have never heard the ones for Leeds or Wolverhampton and I assume they're silly back-formations like Novocastrian. Malagasy seems to be a proper term both for a language and a people, according to Wikipedia, though it's not one I'm especially familiar with. I have no idea about "Haligonian" or the Pittsburgh ones.
I studied all school subjects in Newcastle, and know a great many people from the area who didn't even get to non-signalling-language level of schooling, yet staggeringly, are aware of the specific name for people from Newcastle; you're not an outlier. It's not widely used, but it's very well known.
Here people in Tasmania are colloquially called Taswegians in honour of Glasgow.Tasmanian is proper but I would like to see Van Demons catch on in deference to the dutch name.
Mancunian, Glaswegian, Geordie, Liverpudlian and Scouser, and Bajan are all commonly used. I have never heard the ones for Leeds or Wolverhampton and I assume they're silly back-formations like Novocastrian. Malagasy seems to be a proper term both for a language and a people, according to Wikipedia, though it's not one I'm especially familiar with. I have no idea about "Haligonian" or the Pittsburgh ones.