I got it working! Here's how to do it:
Open app/Resources/translations/(language you need)/AdminAdvParametersFeature.
Go to this github link and select the language you need. On the next window, select the file you need, in our case AdminAdvParametersFeature.
At this point, I copied and pasted all of the github code into a separate file in my code editor, so I can easily search for terms.
Search for the terms you need and paste the related code into the original file. I put them in after the "File: controllers/admin/AdminImportController" section. When I tried to pop the terms in at the end, I got another error (but maybe I made a random mistake).
Anyway, it worked for me. No more "translation not found errors".