I believe this should have been the first sentence we learned. A solid foundation right there.
Why isn't selskap considered as a translation for party?
Because it's impossible to foresee every possible translation. Please use the report button if you get an error for this in the future :)
Why isn't "Hvor ligger festen" acceptable?
If you think it should be accepted you can always report it and it will be reviewed for addition by the admins.
It seems strange to me for a party to "lie" somewhere.