I meant the area of the distortion, the centre line looks to be off centre, over to the left, as though the back of the pleat was sewn to the interfacing out of alignment.
That could happen if the kilt and linings were not lying true during the sewing together.

It is not a huge and glaring error, but I am surprised that it was considered adequate.

I am an utter perfectionist - I once took apart an entire garment for three misplaced stitches, but I would go back to the maker and see if there is someone more senior than the person suggesting that you try to press out the problem, or get more informed advice on just what and how you have got pleats on the skew.

Anne the Pleater.