I just got off a lengthy chat with Matthew Dale, the actor in one of the red box head Jedha Pilgrim costumes. As usual, there's a whole lot more to the costume than one would imagine.
White inner robe
Simple long sleeve T-tunic with mustard yellow lining in the sleeves. The lining only need to extend 6-8 inches up the sleeve. The cut edge of the fabric is not turned in. The sleeve seam is on top. I don't know the correct term yet but that seam needs to stick out(?) of the sleeve. (I'll edit this when I find the right way to say it).
Simple short sleeved T-tunic. The sleeves are elbow length and have hemmed edges a 4 inch wide mustard yellow square must protrude approximately 4 inches from the top and bottom of the sleeve. This sleeve also has that weird hem thingy on the top.
Apron: The apron is a poncho-like garment that extends down the back in a single solid red piece with no yellow showing. The front consists of a straight mustard yellow piece that has a red portion that has two large drapes, one just above the navel and another above the knees. The yellow should be about 1/2 to 1 inch wider that the red on each side.