There was one big scandal about a year ago with some students using a specific examination centre in Greece to cheat.
This lead to Austro examination centres being temporarily suspended in Greece, and a lot of drama. Most of this drama has now subsided.
Austro was, and continues to be one of the most reputable CAAs, and their theory certificates should be accepted by any ATO worth their salt.
Companies generally don't care about which CAA you did your theory module with.
Good luck!