[Answered ]-Django loading templatetags from nested apps doesn't working correctly

You’re using the {% load %} syntax in a wrong way. Accoring to the doc the {% load foo from bar %} loads tag or filter named foo from tag library called bar. In your case {% load test_tag from _project_.apps.newapp.templatetags %} the test_tag is a name of the library instead of a tag or filter name.

So it should be more like:

{% load lower from test_tag  %}