I think we each have a different idea of what understanding is about. My comprehension of understanding comes from my experience.
I think of understanding as being a creation of meaning by the thinker. As one attempts to understand something that person will construct through imagination a model–like a papier-mâché–of the meaning. Like an artist painting her understanding of something. As time goes by the model takes on what the person understands about that which is studied. The model is very subjective and you and I may study something for some time and we both have learned to understand it but if it were possible to project an image of our model they would be unidentifiable perhaps by the other. Knowledge has a universal quality but not understanding.
Understanding is a tipping point, when water becomes ice, it is like a gestalt perception it may never happen no matter how hard we try. The unconscious is a major worker for understanding. Understanding is that rare occasion when there develops a conflation of emotion and intellection.
That is why I say “It appears to me that the explosion of knowledge has reduced our ability to understand.”
I agree that it’s hard to confirm exactly what other people experience and mean.
However one clear proof of understanding comes when other people agree with you.
I apologise if I seem harsh (or even rude), but haven’t you noticed that almost every poster to your threads either disagrees with you, says you ramble or doesn’t understand what you say?
The logical conclusion is (though you clearly mean well) that you have difficulty expressing yourself (and make claims not backed up by evidence).
Summarising hat you just said (at great length!):
People have difficulty understanding each other.
Having vastly more knowledge therefore means we understand each other less.
This does not follow. If we have more knowledge, there are more things we can agree on.