No, "Gurk" belongs to the "the name" of the Diocese, after the former place Gurk where it was located:
Archiv der Diözese Gurk/ Archive of the Diocese Gurk
Mariannengasse 12
9020 Klagenfurt
https://www.kath-kirche-kaernten.at/dioezese/organisation/C2524/It has nothing to do with the 3 findings.
It shows the former place Gurk, but now the Episcopal Residence and Diocesan Archive is located in Klagenfurt, the capital of Carinthia.
https://en.wikipedia.org/wiki/Gurk,_CarinthiaIf you would have more details for Stefanie (shortened Steffi) Krassnitzer, birth year and place you could search for her in the online files. It´ not said, also if she married in Klagenfurt and maybe also lived there, that she also was born there! She could also have been from a complete other Austrian area.
http://data.matricula-online.eu/de/oesterreich/gurk/Yes, the British were stationed in Carinthia. It was within their Zone.
They were in East Tyrol (Osttirol), Carinthia (Kärnten) and Styria (Steiermark).
https://de.wikipedia.org/wiki/Besetztes_Nachkriegsoesterreichhttps://en.wikipedia.org/wiki/Allied-occupied_AustriaSo, on the end of the day - we would need little bit more details.

As how to see, Krassnitzer is not just an uncommon name.
Actual phonebook Austria has 247 results in this states, how to see most in Carinthia.
Bundesland/ states;
Kärnten (187)
Wien (16)
Steiermark (12)
Tirol (12)
Vorarlberg (7)
Salzburg (6)
Oberösterreich (5)
Niederösterreich (2)
https://www.herold.at/telefonbuch/was_krassnitzer/