I've finally received the Mouldking Qinghai–Tibet railway train (set #12001) and the additional coach (set #12001CX). I received both in one box without nice packaging. Combined, you get the engine and two coaches. The train is 7-wide and is larger than Lego trains.
The quality of the bricks is excellent, the clutch power is better than Lego's and the gate marks are as small as those of Lego bricks. There are scratches on the bricks. No parts were missing, damaged or had a low quality. The instructions are ok, but the dark green color is hard to see. The set comes with a remote control, a rechargeable battery box, LEDs and a XL PF motor. A micro USB cable to charge the battery box is included. The remote control allows off and full speed only. There is a QR code to download an app, but I couldn't install it on my Android phone. The building experience was good, lots of interesting building techniques are used. As a display model, the train is perfect. The problems started when I tried to run it. There were lots of cracking sounds from the 90° gears and after a few minutes they were damaged. I could fix that by adding two polyamide washers (see images) to bring the gears closer together. After this modification, there were no issues with the gears anymore, slipping only happens at the wheels but not between the gears. Two 2 x 6 x 2 weight bricks are used to increase the weight of the engine, but they do not prevent slipping. Slipping occurs as soon as a coach is added. The engine doesn't move at all with two coaches. Here's a video where you can see how the engine handles different track elements and an incline:
https://www.youtube.com/watch?v=rWRzCyEosS4 The middle axles of each bogie use the new wheel elements but they are not fixed. There is a high risk they get stuck in switches and derail the train (as can be seen in the video). I made two changes to the engine to make it more robust. I replaced the transparent brick round 1 x 1 with a plate 1 x 2 and two plate round 1 x 1. This prevents that the power-on knob falls out when you turn the engine around. And I've inserted several bars to the submodel below the engine's base.   In summary, the train looks great, but unfortunately it doesn't work. It can only be used as a display model. To run it, a second motor would be needed as well as ball bearings for all unpowered axles of the engine and the coaches. The derailing issue caused by the middle axles would have to be solved as well. Therefore I do not recommend to buy it unless you are interested in the parts like the battery box and the weight bricks.