Hello! Thanks for reaching out.
Unfortunately, I have already tried the support numbers, but neither Czech or the US support was able/willing to help and both pointed at the other as the correct contact.
I did receive the right kind of help here on this support forum before, but unfortunately I provided serial number of the "old" cartridges and so the solution didn't work.
Now I believe I have the right input and just need a HP specialist to generate the right regional reset code, same as before. Please see a private message with the details.
Thanks!