No worries, I will try to give a better explanation.
There are two things I am concerned, the material and the design.
My main concern with the material would be how much shear the 1/4 thick mild steel tubes could handle the machine's weight.
My concern with the design is that it would not be sturdy enough to withstand the weight of the machine even if the steel technically could. The tubes at the top are fastened with one through bolt. Two if you count the bolt holding the lower pipe.
Contrast that with the arms of the machine. Double pipes and a(2, front and back) thick gusset plate at the pivot.
You see the same construction at the front of the arm, 2 gusset plates on either side of the pipes with 6 bolts on the arm side and 4 on the loading side. Also washer to spread the load on the gusset plates.
The arm/bucket is what does the work, so I expect it to be engineered to work.
The machine will not be picking up loads heavier than it, otherwise it would tip forward. So any load put on the roll cage will be greater than the load put on the bucket but I do not see the attention to detail on the roll cage that I see in the bucket/arm connections.
I could be wrong, I am not a design/structural engineer. I work as a production engineer but in a factory that builds highway construction equipment. The designs that I am used to seeing are single steel tube bent in an arch for greater strength. Also you are not allowed to weld or cut holes in the tube as that would compromise the strength.
