You're right about about the stock tires, they're crap. I replaced them with Schwalbe Marthon plus MTb, because I do a fair amount of gravel & trail riding.
I was going to sell mine, but I've decided to keep it and do some simple mods. First thing I did was change the handle bars to a more swept back design. I haven't ridden the bike yet with the new bars but they look promising.
I did have a suspension seat post on it already, but when I decided to sell the bike I put the suspension seat post on my wife's Pedego Commuter. Since she won't give it back I ordered another one.
I installed a mountain bike front fender and got a free, slightly damaged rear fender from my Pedego dealer. I modified it to fit the bike and attaches to my rack.
I also had my torque sensor fail around the same mileage as yours.
My brakes were getting spongy, so I decided to bleed both. The fronts were relatively easy, considering I was using a cheap Amazon bike brake bleeding kit, but the backs were more of a pain. I got all the air out of the system but the brake lever still pulls closer to the handle bars than I'd like. Interestly, last year I had a bike shop do the bleeding and they weren't able to do any better.
I've done the brakes on all my cars for many years and I have to say that bleeding the brakes on this bike was more of a pain. I think using a quality Magura designed kit would have made the job easier and a lot less messy.