bi-amping cable arrangement

Good point...crossing any cable carrying current at 90 is essential if you cannot keep the distance between them wide enough...

Agree with the last post; keep the cables separate with a few inches distance between them...

While I wouldn't twist them, I would cross them at 90 degrees if practical and necessary.

The two runs of wires should be kept separate.
Twisting the single pair (plus/minus legs) has reasons. Twisting up two separate pairs together is a mistake*
*unless the wires are in a 'quad twist' which all four wires stay parallel but twisted together

You have them, make up your own mind.

Were you able to hear a difference between running them parallel or twisted? If so, what were the differences.