in my experience, low mashing pH results in reduced body and mouthfeel. At lower pH, there is likely some degradation of the poly-saccharides or proteins that would typically exist in wort. No data, just my own perceptions of the end results.
It is probably too late to correct that effect via an alkali addition. The only thing that would occur is the wort pH is higher and the resulting beer pH might be slightly higher than if you didn't do anything.
It will still be beer, either way.