I have different resources with a few strings on each. Would it be better to unify them on a resource, so I can translate all of them at once in the editor? How can I filter by priority?
If all those strings can be in the same file, I would say in general would be an easy way to work with it inside Transifex. You also would be able to download translations at once.
If you want to keep this structure with many different resources, you can tag all strings according to its priority using the API as explained here, and the translator will be able to select ALL RESOURCES, and filter by Tags.