Oh please. https://www.expatistan.com/cost-of-living/vienna - it's just as expensive as other European capitals, <10k/y is barely above poverty level - not to mention with kids. Please define 'comfortable' - because to most people, that includes living in a good area in a city or a detached house outside of that, not having to thrift shop for clothes and not having to grow your own food unless you like to. And most likely a car too, even if it's only an old and small one. And not having to worry about whether you have money to get a new washing machine when yours breaks. No way that's possible on e833 a month (assuming e here - $ is even more ridiculous).
You can live like student for 20k/year in Prague, sharing room with other person and dont go out much. Doable, sure but maybe not a great plan for next 40 years.
