This will depend on what type of leather you have.
If the ink is on a pigmented leather then the first thing you should try is an ink stick .
The fresher the ink the more chance you have of removing it. Be sure to check the type of leather you have before doing this as if you use this on an aniline style it will not work and may leave a greasy mark which will not go away.
If an ink stick doesn't work a solvent based remover will need to be used and it may also remove finish and pigment so is best left to the experts.
Using hairspray/WD40/alcohol/perfume etc. and all these other solvent cleaners is very risky as it can make the matter far worse as it can spread the ink over a bigger area and can sometimes then be impossible to fix.
If the finish is unstable this would remove pigment from the leather
Nail varnish remover or any other solvents will also remove the finish and pigment which will need replacing.
DO NOT USE Baby wipes as they are about the worst thing you can use on a leather as they break down the finish and will eventually ruin it.
Magic erasers usually remove finish and pigment along with the ink.
Old ink will be harder to remove than new ink and may mean resorting to solvents which will also remove the finish. This is probably best left to the experts.
Hide food will not remove ink and will leave residues on the leather which will attract dirt and oils.
Using a good quality leather protector (one that works) will help make this problem easier should it happen again, it also does your leather good by protecting it against oils and dirt which ultimately make the pigment crack and the leather deteriorate.
If the ink is on an aniline leather then there is nothing that will work if leather cleaner has not. Basically you have redyed the leather and you would need a specialist to resolve the