That seam isn't horrible it may lay out ok it's hard to say from here. I will say that liner shouldnt have been installed. It happens all the time but it drives me nuts to see all those rocks in the face of the vermiculite. They should be all tapped down or picked out and the wall foam should have been replaced. Personally I'm not a fan of guys that just do liners. They slap them in and get paid on to the next. Not sure if this is a PB or liner crew but they should know better. Hope it turns out ok in the end for you