Another thing you might try
. I notice you are using treatments. (imho) there is a direct correlation between room treatments and the internal dampening of speakers. So what I see is a heavily treated rear wall using heavy internally damped PMC speakers. Since the treatments are already up go into your PMCs and pull out all the internal stuffing. Start with all of it. Do not listen too loud but figure the best internal dampening amount by putting more back in as you go. This will help with the intensity or tension in the soundstage..lightens it up. Makes it sound more floaty ....lol.
PMC's are transmission line speakers and that " internal stuffing " is a big contributor to how those transmission lines work. It is literally part of the design. It is absorptive material which is there to allow only select low frequencies to exit the transmission line. Remove it and you will likely have a
seriously negative effect on the speakers' performance. You will also almost certainly void what I assume is the 20-year PMC warranty.
From your photos, you need to reposition those speakers more than you need to replace them. If there is nowhere else to put them during your renovation, you may have to just live with the suboptimal sound as you could take almost
any speaker, set them up too close to the back wall and stick one in a corner and you'll be no further ahead of where you are now.
D.D.