Research on water roux sweet buns

My curiosity on water roux buns has brought me to many interesting recipes on the web. Here is one that I've drafted out based on someone's original recipe (shown below). I'm going to try it out some day.

Water roux buns in small batch (make 8)
Ingredients:
Water roux
- 1 TB bread flour
- 1/4 cup water
Dough
- 1+1/6 cups bread flour
- 1/2 cup flour
- 1 TB + 1 tp milk powder
- 2 TB sugar
- 1/2 tp salt
- 1 tp active dry yeast
- 1 egg
- 1/5 cup lukewarm water
- 2 TB butter, softened



Sample water roux buns (make 16) adapted from Japanese style bun dough 

Water roux:
- a little less than 2TB (25g) bread flour
- 1/2 cup (125ml) water
Dough:
- 2+1/3 cups (325g) bread flour
- 1 cup (150g) flour
- 2.5 TB (20g) milk powder
- 4 TB (50g) sugar
- 1 tp salt
- 1 sachet instant dry yeast
- 2 eggs
- up to 2/5 cup (75 to 100 ml) lukewarm water
- 1/2 stick (75g) butter, cubed

Procedure:
1. Prepare water roux.
2. Mix bread flour, flour, milk powder, sugar, salt and dry yeast.
3. Add egg. Then slowly add in water. Stir constantly until a smooth soft dough is formed. Knead it vigorously to develop the gluten.
4. Rub in the butter.
5. Set in a bowl and allow to rise until volume is doubled.
6. Punch down and partition into small dough balls.
7. Shape and allow to proof again until volume is doubled.
8. Bake at 375F (190C) for 15-20 minutes.
9. Apply an egg wash or honey wash when the buns come out of the oven.