On reflection, that is wrong. If you apply exposure compensation of say +1EV on your camera at the time you are taking the picture you are just compensating for the fact that the camera’s metering system would have got the exposure wrong on its own. Thanks to your compensation, the exposure is right. But the resulting combination of ISO, F-stop and shutter speed still resulted in correct exposure and so can still be used directly to compute the ambient EV level.

It is different though when you add or reduce exposure in post, using Adobe Camera Raw, Lightroom, Aperture, etc. In that case, if you say added exposure it’s because the actual combination of ISO, F-stop and shutter speed resulted in underexposure, so the ambient EV was lower than implied by the ISO, F-stop and shutter speed actually used in the shot. So exposure added in post translates to correspondingly lower EV and vice versa. Hence the -expadj term at the end of the formula.