Sliding Gate Mis-Aligned After Repairs

Exactly what Ray said. If the guy took the gates down, would have or should have placed them on a steel bench secured the good part to the bench with clips and tacked to the clips, ran a heavy angle or tubing, whatever is hand across the gate.
The whole idea is to prevent the gate from moving when the bottom is cut out. Welding a thicker wall steel or thicker material is great but it requires more amperage which means more heat which means distortion
MIG would have been my choice but if it was stick welded thats even more heat
If the guy left the gates up, did the job in place and didnt weld braces across the gate, there is your answer
Bottom line is if the gate functions fine, get it to look proper to the naked eye and forget it
You would not get a lot of shops in this country to fix those gates for exactly the reason they turned out the way they did
Most shops here would tell you it's not worth the labor and effort involved. In other countries there is a different mindset that you fix whats broken before scraping it
I still say as far as the pictures show me the guy did a ok job all things considered