How does strength of boric acid solution increase in presence of salicylic acid?
Equilibrium will be far to the right, as a stable six membered ring is formed. The proton speaks for itself.



References: Queen, A. The kinetics of the reaction of boric acid with salicylic acid. Can. J. Chem. 1977, 55 (16), 3035–3039 DOI: 10.1139/v77-421.