I think you are correct that something has changed in the processing of such templates.
Using this:
trigger.device_tracker.attributes.friendly_name
in the template of an automation used to work perfectly up to 0.116. I had to change it to:
state_attr(trigger.entity_id, 'friendly_name')
My hunch is ‘entity_id.entity_id’ might need rephrasing as well, but I’m sorry I don’t know how to rephrase it.
Edit: you might want to raise a bug report anyway since the documentation you linked to is also faulty right now, needs fixing anyway 