Templates & Relations v Type & Relations

Relations are per-object, you can add any relation to any object that you want regardless or template or type.
When you “add” a relation to a type trough the library, you’re only adding a suggestion that will show up in the relation menu of every object of that type. You’re not technically adding those relations to those objects.
On the other hand, when you add a relation to a template, you are adding the relation itself to to template and any object that is created trough that template.
These are all separate things. This way, you can add relations that should be used in all of your objects of that type to that type, and then only add relations that you want to be used in specific templates to that template.

Yes, templates are a manual process right now. Hopefully in the future we get the ability to automatize them. Something like this: