My current diagram for communication among the levels of the mind with the higher self depicts the following: The higher self and the deep subconscious can talk back and forth seamlessly; the higher self is aware of what the conscious self and the upper subconscious are thinking but does not talk to them directly—only through the deep subconscious; the deep subconscious is also aware of what the conscious mind and the upper subconscious are thinking, but cannot talk to them. Is this all correct?

This is all absolutely and 100% correct. You have nailed this down with precision. The intuitive gateway is an aspect of the deep subconscious. It is the only way that the deep subconscious can reach the upper subconscious or the conscious self, so in a sense it is a bypass mechanism but it is not possible to have seamless interaction at the level of a conversation. It is a very inefficient and incomplete experiencing of impressions. These can be sometimes reinforced with knowings courtesy of the higher self, but this is a very fragile and fleeting and only partial awareness and ability to communicate at best. So, in effect, for the average person, for all practical purposes, you can say there is no direct communication by the deep subconscious because that is strictly correct. There is, at best, some intuitive reach but that is present to only a minor degree and happens intermittently and mostly under circumstances where there is a highly charged emotional need for the awareness to get through, but this will only be successful for a low percentage of people. Most have too little intuitive awareness for this to be a useful pathway for communication within the self. It is too unreliable, too fleeting, too ephemeral, and will, as often as not, be ignored as a guess rather than a knowing. So people may rely on a gut feeling but many times will not, so it is a system that for practical purposes has very limited value. The true communication possible is simply not happening in a way that would be true with normal functioning.