Same here (Czech Republic). My address contains diacritics and after the error message on that input field, removing diacritics > submitting, I see that Apple changes the chars, e.g. from "s" to "sh" where š would normally be. Submitting the corrected by them variant leads to the same error. I wrote to finance with the error flow description and referring to this thread.
[Update] Reply from the Finance came instantly with the following solution that worked:
Hello,
Please attempt to make this update from the Agreements tab, and not the banking tab.
From the AGREEMENTS tab, click on the paid agreement’s name that requires a banking update. Examples are “Paid Apps”, “Paid Books”, “Music”, “Video”, etc. You have to click the words (agreement name) even though they do not have a blue hyperlink.
You must be on the AGREEMENTS tab, not the Banking Tab
Under Bank Accounts on the AGREEMENTS tab, scroll to the right and click Edit
From the Edit drop down menu select from:
Edit Current Account
Update your bank account holder address
If the message asks you to verify your banking, click SAVE again. If the message persists, please click save 3 times. Please be sure to let the page refresh before you click it again. This should resolve the issue.