I think there is only one thing we should focus on: Measurable capability on tasks. Understanding, memorization, reasoning etc. are all just shorthands we use to quickly convey an idea of a capability on a kind of task. Measurable capability on tasks can also attempt do describe mechanistically how the model works, but that is very difficult. This is where you would try to describe your sense of "understanding" rigorously. To keep it simple for example, I think when you say that the LLM does not understand what you must really mean is that you reckon its performance will quickly decay off as the task gets more difficult in various dimensions: Depth/complexity, Verifiability of the result, length/duration/context size, to a degree where it is still far from being able to act as a labor-delivering agent.
