No objections from me.
Re: Serbia - because the secondary sources (and paper primary ones too) treat the three digit roads as different to the 2 digit ones, I treated them different. When making the system detailed info was pretty scarce and I don't think I'd seen that they were signed the same. They do have a different, hidden, prefix though so I'll probably add them as a separate system when I do my (long time coming) Serbia clean up that I nearly started when doing a flurry of tier
5 systems.
Returning to Austria, the parallel is Slovenia, where the tier 5 system consists of about 4 different levels (with the first number being the distinguisher of that). I don't believe they are signed differently (unlike say, Spanish tier 5 roads where I've taken the orange cartouche roads, but not yellow, green, etc cartouche roads that are at a lower level), so were treated as one.