I've just added a test for relative template paths that include "../" at the beginning:
This test passed immediately, so it seems this functionality is not broken in the 3.0 branch at least. (3.0 does include all changes that went into 2.2.0.Final.)
I notice there are a lot of "../../.." in the template path you referenced. Is it possible you've moved your template outside the GWT module that the @Templated widget is defined in? Errai UI uses GWT's resource system to include template files in the client bundle, so you do have to keep them within the GWT module they're referenced from.
Thanks for testing my guess about "../..". I guess that is not it, but I still can't compile my code with 2.2.0. :-(
The problem isn't that the templates have moved. I tested 2.2.0 just by changing a variable in my ant build.xml from 2.1.0 to 2.2.0. It compiles fine with the former, and errors out with the latter.
Can you think of anything else I should try?