The README file is generally not going to be modified - or seen in
isolation - so it's not so necessary for the end user to know its
license from the file itself.
However, the template files are specifically designed for
modification, and are likely to be seen without the LICENSE file, so
IMO the enduser should see the AL header as part of the file.
That would be my thinking, too.
Not in this specific case, I think.
The original template files are not modified directly, neither are the
output files. Modifications are by token replacement in the simplest form
or by creating a completely new template to override the original (at which
point the user can define their own licence).
If the user generates their widgets from these templates the files we are
talking about will be included in larger files, which do contain license
headers. Final outputs will therefore always have an Apache header, there
may be user specified headers surrounding their own contributions.
The final outputs should never be edited, it's the widget definitions (the
tokens referred to above) that get edited.