You're overthinking it. It isn't necessary to list every country. Combine them and use "various" or name the largest of them.
It only matters if you have income or taxes to pay from sanctioned countries that don't qualify for the credit (such as Cuba) you can simply list various and no one at the IRS is going to come running after you.
Keep your detailed records in case they ever ask (which is highly unlikely because doing so will not produce any additional revenue) and just combine them and save yourself the headache.
