Going back to the initial question from delicado you were referring to (no bulk categorization for foreign currency transaction?). Yes, it's clear QBO do not offer this functionality. Foreign currency transactions need to be categorized one by one to allow currency conversion no matter how you get transactions in QBO. I share his disappointment and frustration.

Now since I had 5000 plus foreign currency transactions to categorize one by one, I founded quicker to do if you already map them to the right category in Excel and upload them in a cv format into QBO. Then you'll need two clics per transaction to add them almost mechanically. You can open up to four QBO window at the same time.