This is how they can fix it:
Aesthetics: Replace the harsh ceiling lights with recessed alcove lighting along the ceiling lines. Install wall light fixtures in the style of gas lanterns to maintain the existing look of the station. Install a false ceiling with a mirrored finish to give an impression of height and perforated to help eliminate echo. The wall at the end should be removed. Why is it even there? I'm hoping that that is yet to come as they open up the walls leading up to Maple Leaf Square. That might bring in some natural light.
Logistics: Install a PA system and an asynchronous check in and boarding procedure. As you arrive at the concourse down the ramp, you use a terminal to print your tickets and weigh your bag, getting a tag to attach to it. Roaming workers help with check ins and ensure nobody is cheating the system. You wait in the waiting areas rather than in a line. The screens at the gates show the gate number, destination, status and boarding time. When boarding starts, announcements come on the PA: Now boarding car 5 to Montreal at Gate 9. Announcements should also sound in the Great Hall so that it becomes another larger waiting area to keep crowding in the concourse down. After they go through all the cars, an announcement stating that general boarding is now open so that people can just walk up to the platform. No need to wait in lines.
If this sounds familiar, that's because it is. The airline industry has long figured this out and done boarding pretty well for decades.