TBG, I need more than apocrophal evidence that direction matters, since I don't even detect any difference in even 'ordinary' fuses let alone 'directional' ones.
By the way, what is directional about these fuses, besides the arrow (I presume) marked on them?
As for speaker wires not having anything to do with this, - well, I use them as an illustration of why directionality has no effect on circuits or wiring when they deal with AC currents, grounded or not. Perhaps you object to my use of that example because you have no evidence that I am incorrect about that.
Remember that a fuse is just a short piece of wire with the added property of melting at a given temperature, the heat being caused by the current through the wire, changing direction continuously.
Salut, Bob P.