Propanediol or Propylene Glycol AND Polysorbate (some numbers of your choice).
But you would need A LOT of Propanediol/Propylene Glycol (depending on the amount of Salicylic Acid).
Surfactant such as Polysorbate lessens the use of those glycols as it also helps with the solubility of Salicylic Acid.
You could add in Alcohol.
Alcohol is the primary solvent of Salicylic Acid in corn/callus/warts remover.
The more solvents mixed together the merrier. It means you use less of either one, by doing this it reduces whatever irritation that one substances may cause. Similar to a mixture of preservatives is normally more effective and less irritating that maxing out on only one preservative and hoping that that one preservative is Godly.
There is some things for everyone to be sensitive about anyway.