The turning out or rolling of the pleat is not unusual - I cure it on my own kilts by lifting the inner fold of the under apron pleat up so there is a small triangle of doubled fabric visible above the top of the apron.

That pulls the pleat back into line.

On an already sewn kilt I think that a horizontal dart several inches below the waist (where the outline will not be visible though the apron) will do the trick. It should not need to be very large - but you can fold, tack and try on to see how much needs to be done to fit the kilt around your shape.

Anne the Pleater :ootd: