I've accessed both 13 and 16 models on the these Mazda doors 8 times in the last 2 weeks working on projects. Each time I place the door panel back I double check for "pinches" and ensure the window goes up and down smoothly. If it pinches I just readjust the rubber/felt channel thingy whatever its called. It has to be lined up correctly otherwise you'll hear a cracking sound. This rubber part is attached via plastic tabs unto the plastic door panel WHILE also pinched into alignment on top of the metal door frame. I suspect some having problems with their windows involve this part not being secure. Again it needs to be correctly/firmly secure to both the metal door frame and the plastic door panel. The earlier 13 models are actually easier to work on imho.
The actual window regulator is bolted onto the metal door with 3 bolts. It was on there pretty tight and I can't imagine it being loose. If so then it's an easier to fix than having to secure the rubber/felt runner adjustment as noted above. That said I can totally see a Mazda tech get frustrated and be satisfied with a partial fix due to not having everything lined up correctly. You have to hold the plastic door panel in the air next to the door, ensure the wire connects are plugged giving you about 3 inches of slack, oh and make sure the door handle doesn't fall off (it does), you have to angle the rubber/felt channel correctly unto the metal door frame. All of this at once!!!
The first time I did this it took me a good 2-3 hours just to get this one part right. After doing it 8 times (2 cars) I can do this one part in about 20-30 minutes now. Most time consuming part of taking apart/reinstalling the door.