I don’t know if it helps but the Honorary Consul for Salzburg Dr. Harald Kronberger also runs a legal firm and perhaps he or his firm might be able to give you some pointers: https://www.eulaw.at/en/lawyers/harald-kronberger/
You can of course join our Facebook Groups too: https://www.facebook.com/groups/BritishAustria and for Visa/Residency questions, this one is better: https://www.facebook.com/groups/BritishinAustria