OP,
First of all, I am really sorry to hear the problem you are having. Second, there is something very wrong. We have had a great home theater system and a bedroom system (currently a 65” with a Sennheiser Ambeo sound bar) for at least 30 years and never experienced anything like you are. Dialog (typically 85+% on center channel) has always been really easy to understand, never difficult to understand in the least. Your speakers are good and unless completely defective cannot be the problem.
The problem has to be something very big… nothing little like your center channel angle.
When you go through the surround equalization procedure tne center is at the same volume to you as all the other speakers?
The only thing that comes to my mind is your surround processor has a faulty center channel.