How does it matter what way up you put a haki beam?
The only difference will be what way the end support face up or down.
How many times over the years have you done a simple bit of beam work ie 2 x 6m or 8m haki beams bridged from 2 independants over something yet the beams are different!
some have more straight upright supports than others so cant allways get your tie cords transoms where you need them anyhow.
Also some you can fit doubles beetween the small V's a lot of them you can't.
Steel Unit beams go either way whats the difference?
Also remember the days of using steel unit beams to do temp roofs, we all try putting the beams all the same so the angles meet each other when joining but then sometimes you need to flip them so the fish tails line up and so the angled supports dont follow suit.