Can widget Templates (Template.pt) be overridden with jbot, for example from a theme?
Should be possible. If you ask: is there an issue?
I did a quick test (before I left work for the day). It did not work, but maybe did something wrong.
I did a (quick) read of the description and it said:
Any template that is defined as a class-attribute can be
overriden using jbot, e.g. those used in
views, viewlets and portlets.
So it did not mention widgets, but maybe it is (still) possible
@espenmn Can you show what you've tested and which template you want to override doesn't work? It's a bit vague now for others to respond in detail.
I added
Products.CMFPlone.browser.templates.title.pt
To my theme/template-overrides folder and the changes appeared on my site
Then I added the same file to browser/overrides (and changed it a little) and it also worked.
Then I did the same thing (added to the folders)
collective.z3cform.datagridfield.datagridfield_display.pt
Trying to override: https://github.com/collective/collective.z3cform.datagridfield/blob/master/src/collective/z3cform/datagridfield/datagridfield_display.pt
But the changes were not 'happening'.
You're going to have to do some deep reading, modifying forms is an interesting and challenging task
Start here, don't skip anything...
https://docs.plone.org/develop/plone/forms/z3c.form.html
https://z3cform.readthedocs.io/en/latest/