People shouldn't have to learn a new nomenclature. If third layer remains non-normative, okay to call them techniques. Little question that we will still have checkpoints. The bulk of the checking would be done against the third layer. For a given second level checkpoint, there are various ways of implementing it.
Some technologies have more than one way to do it.
Some have no way to do it. There will be lots and lots of techniques. Testers will not test whether or not there is a text alternative. They will test for alt text on img tags. In well-designed languages, there is an appropriate way to address the requirement.