Understanding XC vs XF Lenses for Fujifilm X-E4

The front command dial will adjust the aperture of a Fuji lens without a ring.  The X-E4 manual describes the default operation on page 67.

X-E4 manual page 67.

Yes it is confusing.  I tried it with shutter dial set to P and Exposure comp dial set to a specific number (not "C") and aperture ring set to "A" (operates the same as if the lens has no aperture ring).  And I had ISO set to 3200.  Lens is Fuji 27mm F2.8 Mark II.

Each time you press in on the front command dial a little notation pops up briefly in the viewfinder indicating the function.  In my case the two were SS and F, and pressing would select one and then the other.  So you would select aperture, and then every time you turn the front command dial it will adjust aperture and then in this particular case the exposure will change so the shutter speed will change also, so you have an exposure selected by the EC dial.  If you press the front command dial again it will indicate "SS" briefly and then the front dial will do program exposure shift, so that the combination of shutter speed and aperture satisfies the setting on the EC dial.

Basically if you set the front dial to "A" you are shooting in aperture priority, and the camera will set the shutter speed to satisfy the setting of the EC dial.  If you have enabled the display to show shutter speed and f-stop, a little half-disc will appear over the F-stop indication to show you that the front dial is adjusting aperture.

The X-E4 remembers if the front dial is set to adjust "A" aperture or "SS" program shift, so when you turn it off and then turn it on later you will still be adjusting the parameter you expect.

I never use this stuff, and I didn't try other things on the table on page 67.  But after using the camera this way a while it got pretty intuitive, and this should happen for you also.  You just have to play with it for a while.

Good luck!