I bought 4 of these for my strats and teles.
First of all, there is no washer included in the set.
Second, the hanger parts are identical with a single wide screw hole. They are not different designs. Third, I can't say that the screws in the set can't carry the weight, but I would feel safer with longer screws and thicker material for the hanger. When I put my strat/tele on the the bottom part of the hanger flexed down with the weight of the guitar which worried me. However, after leaving all the guitars on the wall for 2 hours. I can say they are stable.
In short, there is room for improvement for sure. Such as fixing product images or the content of the kit, using longer screws and thickening the parts. Without these improvements, I wouldn't dare to use this kit for a heavier instrument such as a jazz bass, unless I hang the guitar with an angle that both parts of the hanger share the weight equally.
So, I would contact Thomann for details before ordering if I were you.