Spondylolisthesis.l3, 4-5 slipped off.surgery fixed l4-5 but not l3.was it done right?now having pain on right leg.(had pain on left leg before surgery

Depends on multiple : Factors. It appears your symptoms are mainly leg pain, and hence a surgeon may have decided that the l45 was the only level with stenosis or pressure on nerve, and wanted to to do only what was needed at the time, and not what maybe needed in the future. Difficult to tell without seeing your prior images, but could be an okay decision. Now, you have to consult with a well trained spine surgeon.