There is confusion between paths to views and layouts (see yii\base\Controller::render(). For views there are four formats: “path alias”, “absolute path within application”, “absolute path within module” and “relative path”. For layouts there are three formats only. But they confuse developers because of they don’t match the path’s formats for views. For example the absolute path for layouts does not match the absolute path for views (in one place it begins with one slash, in other it begins with the double slashes). I think it is possible to make them all similar. I think it is possible to make four path’s formats for layouts simultaneous with path’s formats for views.
It will be easy to undestand. There will be one scheme to easy remember.