My question is why would you want "warm" speaker cables? Don’t you want accuracy?If a system sounds a little cold, a warm sounding SC may get it to sound neutral - I.e. a more accurate reflection of the original sound. Or get it to sound more to your taste even if not necessarily accurate.
If you want warm sound, just turn the treble tone control down or use an EQ.
Tone controls don’t have the same effect a cable swap. You also need to consider an EQ means adding an additional component and an additional interconnect which will definitely reduce accuracy vs. a one-for-one trade of speaker cables which probably won’t reduce accuracy.
That said, many folks do use tone controls and EQs, so they are viable alternatives