Adjusting PH for tartness

I was looking at the Surly Cynic Pro Series recipe. It includes 12oz of acid malt. I’m guessing this is for a tartness and not for mash PH? Is there any information out there on the effects of deliberately lowering the PH with acid malt of lactic acid for a tartness that would typically come from bugs etc? My thought was to mash in a regular range then add the acid malt at the end which would drop the PH to around 5. But I’m not 100% what effect that would actually have.