I also think that without knowledge of that specific area it would be very hard to solve.
Yes, it was deliberate ;) I was planning to lead people towards the area with some clues, such as writing something in Cieszyn Silesian. But I was really motivated by encouraging anyone reading to learn more about Zaolzie - if you get the chance, I'd really recommend exploring the whole area, as it has a very very interesting feel about it, even down to the bilingual use of Polish and Czech.
'New' Skalmierzyce was a customs post on the border and adjoins Skalmierzyce.
Bingo :D For an extra point - what was the meaning of "you need to go next door to get your identity card"?
Now to think up another fiendish riddle...