The story continues. I paid via paypal, but apparently paypal processess all the payments in USD. Because my reservation has been converted to Euro, paypal withdraw from my account the Euro amount in USD causing e-ticket not to be issued. (if it passed, it could be a very decent fare )
After today's call a miracle happened. The agent told me two options: to pay via paypal again, after she converts the amount to USD or she takes my CC details over the phone if it is CC issued in Europe. (The agent I was doing the booking with, told me I need to pay in person )I went for the second option, no issues with Slovakian billing address, the payment went through and was confirmed by agent. After waiting for couple of minutes and e-ticket not being delivered I checked my account and found out CO took precisely $1 Way to go CO

And for the billing address it can be even Mars - as it was said as payment clears CO doesn't care