Hi Tom,
I don't have the GR yet, but I think I (sort of) understand how the AEL/AFL/C-AF switch works
If the lever is switched to AEL/AFL position and you press the focus button, the camera does the focus/exposure (or both) lock. According to the GR user guide, the default [AEL/AFL setting] is focus lock. So if you prefer to use the AE lock, change the [AEL/AFL Setting] to AEL.
Now if you press the focus button, the camera should lock the exposure. By default, the AE/AF lock is kept as long as you hold the focus button. Luckily, there is an option in the camera menu to change this behavior. The [AEL/AFL Lock Setting] has two options...
Off - the lock is kept as long as you hold the focus button (default setting)
On - first press of focus button locks the focus/exposure, the second press cancels the lock.
Maybe it sounds complicated, but I think the real use is much easier? It all depends on personal preference of how the AEL/AFL lock should work.
Hope it helps?