OK, I investigated this, and it's just a matter of an incorrect keycode definition in raylib-go, and so should be fixed in the next update.
As for seeing left or right control as both being recognized as "control" in general, I'm reluctant to add this kind of a feature because on different keyboards, the keycodes could be different (i.e. left control and right control on my keyboard layout could be a different set of unrelated keys on a different computer, maybe?). To cut down on that, it seems logical to just have it work for the specified keys and not (implied) additional ones. I'll have to investigate and see if this is a valid concern.