I'm not sure what you all are currently using for testing, but it sounds like you may need to start with getting everyone on the same page as far as testing tools are concerned (I know, way easier said than done.)
Whether that's deciding to consistently use Google forms, jotform, Lyssna, UserTesting... or even just deciding that wherever tests are conducted, that they be exported into the same format. Then, you could either organize those results directly in whatever application you are using, or exported and placed into a "repository" of sorts, like Dovetail or Google drive. Consistent naming conventions would also be beneficial here (because what good is it if no one can find it 🙃)
Hope this helps Giorgia N.!