Does anyone know the "simple secret" of creating these blocks in the modified stack and whack version?

Not sure about what you mean with modified stack and whack, but I have made a couple of hexagon stack and whacks. I have not done a One Block Wonder yet.
For mine, all triangles were 60 degree triangles and I cut six matched layers for the blocks, and two triangles (same size) from background fabric. I sewed the hexagons together, and then sewed background triangles to opposite side of each hexagon. This allowed me to sew them into rows.

For the One Block Wonder, you sew 1/2 hexagons, keeping the matching two together, and then use a design wall to lay them out. Sew the rows with the 1/2 hexagons, and when you sew the rows to each other, the hexagons should match up with their mate.

It is how you arrange the equilateral [60 degree] triangles that make it look like a hexagon.

Use some graph paper of just plain 'ol lined paper and draw two parallel lines. Then use the distance between the lines for the sides of the triangles. You can save time by doing all the horizontal lines at once then just measuring for the sides of that first triangle and keep going from there.

____ then add ///// then add the opposite sides of the triangles.

Sorry, my keyboard expertise isn't that great.

ali