I believe comm errors would refer to the serial data link between the display and the controller. If you have a broken wire or loose connector, it can be simple to correct. If it's a noisy system, I suppose it could be quite problematic. It's mainly Display --- Harness--- Controller. If you eventually replace all three, it will probably go away, Won't Mokwheel customer service respond under warranty?
Tapping the brakes causes the controller to notify the display, This might poke it out of its "Comm Error" status to show a normal screen. If you are riding, the controller gets its throttle and pedal sensor input and tries to run the motor, Then the display must try do something else that results in the Comm Error again, and it shuts down the motor.
Since you have a torque sensor, the third party controller isn't a viable option. Normally with simpler ebikes, the controllers plus displays are often replaced with something that works better and is less money than paying the bike vendor markups on their units. You're probably replacing with Mokwheel parts. Not to say that you couldn't do it with off-the-shelf-parts, but it would likely be $200-300 USD.
If you're desperate, and a good tech person, you might look at the display-controller pin connections. If it's like most displays,
it can be bypassed, but only if one undertands the interface.