authenticity of pattern in question

[Chef]

Sounds like a good post for the DIY forum.

[The Wizard of BC]

I bought that same pattern just to see what it was like. Plus I thought I could use the pattern for the Prince Charlie jacket.

It is no way authentic. It is designed for costumes. And nothing else.
It has you cut out the pleats in rectangles before sewing. It has no interfacing or stiffening built into it. It also completly skips over Steeking, proper pleat layout, and apron tapering.

If you want to know how to make a kilt, get a copy of Barbs book.