Any idea how quickly the Austrian inventory would release if I cancel?
It could release instantly. It could never show up at all. You just don't know.
Generally, a mistake of one letter is allowed and there should be no trouble in actually traveling. If the airline noted your record there shouldn't be any problem. This sort of thing happens all the time.
If I were in your shoes and they couldn't guarantee a cancel/reissue without losing the space I would leave things as is. The biggest problems in these cases are generally related to mileage credit (n
t an issue here - but on revenue tix one has to ask for proper credit) and elite benefits (FF# doesn't match reservation so upgrades, priority boarding, baggage limits are lost). I speak from experience, and the country I was traveling to required a visa. All went well.