I had bit more complex post about this later somewhere but any such math would be pretty useless practically because the value is inverted anyway.
But "absolute" EV values are not used in photography either...for at least two decades, since inception of digital cameras.
EV is primarily used as "offset" ( i.e "+2 EV" meaning two stops more light ), not as absolute table value (i.e "2 EV" being exact number resulting from combination of shutter and focal length normalized per ISO).
Why would you even need this? The full settings (Sensor size, ISO, Shutter, Focal Length) are identical between Corona and cameras. None of my cameras (Sony Alpha 7r series) have option to input absolute EV value, it's long abandoned concept.
I am of opinion that Corona should go full way and allow EV modification even in full settings, so that is it absolutely identical to how digital cameras work. You set your settings (f-stop, shutter, iso..) and still have option to use EV as offset.
I'll make that a request when I'll remember.