Cables not quite being the correct length seems to be an almost perennial problem.
If the cable is plenty long enough overall, I have resorted to slipping the nipple off the plastic coating,
and snipping off 2 or 3 turns of the spring outer underneath.
This requires a strong pair of wire snippers, and some fairly deft cutting so as not to mung up the whole thing.
While this is obviously not quite as good as finding the correct length cables,
it goes a long way to correcting cables that are not quite right.
Cables that are overall too short probably need to go back to the maker,
although we appreciate this isn't always well received, or economically viable....
Good Luck !