Hello James,
yes, you can upload an Expert Advisor back if you go to the strategy editor, and after that, you click that arrow down on the left side of the Data resource:
Also, if you want to import not just one but whole portfolio or let’s say the 10 EAs from any of my courses, you can use the Validator.
Drop them there, filter if you wish with acceptance criteria and Monte Carlo and press Start. The EAs that go trough will show in the collection.