I also had to hassle with location when I first established an account, but it now seems to know I am in the US. So when I do an automated checkout, the shipping is €30. That is also clearly laid out in the USA row in their shipping costs table:
https://www.rombol.de/versandkosten/.
So I am both surprised and excited to hear that via e-mail you recently got a better deal

. I'll have to e-mail them directly and profess checkout difficulties like you, and see what they say...
-Mark