I never heard of "Directionality" but there ARE 2 different ends of the wound strings in particular.
Been a while since I've changed any classicals but I seem to recall in my youth there was an end that had "looser/spaced" windings.
You got my curiosity up and I found a discussion that recaps the real issues here:
https://www.classicalguitardelcamp.com/viewtopic.php?t=112160
Including this quote from well-known luthier Dan Erlewine:
"Most wound classical strings have a limp end and a stiff end, while the unwound treble strings often have a plain end and a colored one. The limp end of a wound string is simply a result of the manufacturing process; it is not meant to be tied onto the bridge, although many guitarists mistakenly do this because it’s easier to wrap. The limp, loose, wrapped ends break sooner, and will not only mar the tie-block inlay, but scar the saddle as well, causing buzzing and intonation problems. Often the treble string ends are color-coded to identify tension (red=high; yellow=super high). Don’t tie the colored end to the bridge! As Jeff Elliott points out, “The color can transfer permanently to the finish of the top or the bridge, so I either clip it off or use the uncolored end.”
Ah, I see Brad got in while I was still composing but this confirms his impression.