Honey is acid because it is a mix of glucose and fructose which have loosely bound hydrogen ions as part of the sugars' six carbon chains.
Syrup (a solution of sucrose) is basic because there are fewer (ie negative log) hydrogen ions available.
Honey bees possess the enzyme to catalyze the hydrolysis of sucrose in their crop. This enzyme is added to syrup or nectar, and the syrup is inverted and becomes acid in reaction by the action of the bees ingesting it.
The bees possess everything they need to make honey in their crop from the inputs of nectar (a mix of sucrose, glucose and fructose). The addition of a hydrogen donor such as citric acid, or vinegar simply inverts the sugar in solution.
Inverting sugar "sweetens" it because a molecule of H20 is incorporated into the carbon rings in the process of hydrolysis. The bees use hydrolysis as a way of increasing the concentration of the raw nectar without evaporation.
Hydrolysis is splitting the double ring of sucrose in the weak middle link:::
Fructose in solution adds and loses hydrogen+ ions from the ring freely. Note that the sugar has a one or two carbon side chain, with an O-- atom occupying a ring position. The O bond with adjacent Carbon releases a H+ from a hydroxyl group. The nomadic H+ is what raises the log availability of H+ in the solution.
Ascorbic Acid is an unstable ring with loosely bound hydrogen

I have found that vinegar induces robbing.
You can feed unlimited amounts of simple sucrose syrup and the "honey" produced by the bees feeding on it will still be acid. It is acid because that is what fructose solution are intrinsically, not because of adulterants added to the syrup.