I had a x2. I’ve been sat puzzling why you would need to change the the f stop with TTL metering till I remembered the lens on old SLRs etc. did stop-down exposure. i.e. the lens stayed wide open when you looked through it and when you operated the shutter, the lens stopped down to the set f stop and then would open back up. There was normally a lever on the lens that told the camera meter what the lens was set to and it knew what the shutter speed was so it could tell you the exposure was good or not.
When you put a converter on then you got less light. Mine was a Pentax K-mount and it had an offset f setting lever. i.e. the lens lever said f5.6 but the converter lever that was pushed by the lens lever was cranked so it told the camera f8. The TTL metering worked just fine that way.
My old Asahi Pentax S2 SLR (1959-1962 vintage) has stop down metering but the lens remains stopped when you take a photo. You have manually cock the lens ready for the next shot. I keep thinking of getting it cleaned up and calibrated as it as old as me. But then why…? It may be a vintage SLR but it’s effectively worthless as most 35mm SLR cameras are. Just a few of the Nikons have real value and it’s not one of them.