The Hayter-Braeloch Scale

[Welsh cake]

3. Apatheist
Those who are uncertain regarding the existence of gods. They may sometimes 'believe' and other times 'not believe' that gods exist, and question whether the issue has ultimate consequences.

I'd argue that Apatheist is summarised and consequently is missing out its crucial various states of certainty or 'uncertainty', whatever, these states are what most theists go through when they gradually convert to atheism, because you can be 'Apathetic Agnostic' as well. When I began to de-convert I became gradually an apathetic theist towards the belief in the god concept, yet still thought a creator-like entity was responsible for the entire cosmos, but at this moment in my deconversion I felt indifferent to it, I studied the Problem of Evil and concluded it didn't care about my life (or my eventual death) and thus I stopped attending religious events or ceremonies, I ceased praying, or conducted any other form of action relating to god.

You mention the only measure useful is of "certainty" that appears in the scale but those who are "uncertain" are Apatheists, I respectfully disagree, these are in a nutshell simply varying levels of certainty again given how they exercise and express their belief or disbelief in their day-to-day lives, you couldn't identify an apatheist but the belief in god(s) is still a binary position and we can't have an 'in-between', in other words, to suggest they are uncertain is to subsequently imply they are somehow capable of accepting both positions of belief AND non-belief in a god which is a logical contradiction.

I would say you have many more varying levels or degrees of certainty resulting in one being transcendentally Apatheist Theist or Apatheist Atheist or Apathetic Agnosticism. These similar but distinctly different positions are quite complex to differentiate and it requires more careful thought because you could feasibly go the extra mile and include Ignosticism into the fray.