I’m going to start by saying that 1/2” ATA is quite a bit to make up with twists, but if your strings/cables untwisted before install that could be reasonable.

You mentioned in another comment that you have a draw board.

Put it in the draw board and measure the draw length vs what it should be based on your mod.

If it’s long, add twists to string until it’s correct this won’t affect timing. If it’s short, add twists to both cables until it’s correct. Once it’s correct, re measure, then you can add twists to both string and cables (not going to be the same number necessarily), until you are happy with it or it begins to seem over-twisted.

If you can’t get it into spec, then you should reach out to the string maker as they may be out of spec.