I don't think that this kilt has been sized down that much.
If you look at the under apron strap it appears to have been moved about 2-3 inches.
This is about the same that the right side buckles appear to have been moved.

It would be the hem that concerned me. To alter a kilt like this you would normally do it from the top down. This is so the bottom of the Fell stays at the crest of the hips and buttocks.
I suspect that the wearer wanted to wear this lower than it was designed to be worn.

If you let down a hem like this the crease will never completely go away. Especially if the hem has been in for a while.

And when the kilt was pressed after the hem was put in, whoever did the work did not keep the creases straight. I doubt that his kilt hangs as well now as it did when new. I will almost bet that the back of this kilt shows the 'shower curtain' folds that are so common on a poorly pressed kilt worn low.