Win 5.0b Beta 3
Create a custom guide template, template type: Topic
Put in it whatever you want (I've tried both "Definitions" alone, and "All Sections from Topic Guide")
Give it a name, and close the template.
Now try to run a guide from that new template, but you can't find it in the Guide menu. It's nowhere to be found.
You can tell that the template was saved internally because you can reopen and edit it further by accessing it via History, but there's no way to run a guide based on that template.