AMEX Platinum (personal)
MAY 11
AMERICAN AIRLINES 45DALLAS TX
$525.00
Category: Travel - Airline
MAY 13
AMEX Airline Fee Reimbursement
-$200.00
I know the old T&Cs explicitly stated the credit would work for day/annual lounge membership passes, but they no longer explicitly mention lounges.
I got an Admirals Club membership, and as you can see, the reimbursement went through fine (even with a general category coding of "Travel - Airline").
EDIT TO ADD:
It shows up as an actual flight on my AMEX with the following "flight details:"
Passenger Name: [my name]
Date of Departure: 05/11
Ticket Number: [what looks like a valid AA ticket #]
Document Type: CLUB MEMBERSHIP FEE