I think the Centurion benefit requires flying on LH group flights and UA doesn't count. I also thought that the GS benefit extended to GS flying in business class departing FRA when GF went away, but haven't heard in ages and assumed it expired or I didn't remember it right. It never extended to FCT and it's a bit inconvenient in that there is no FCL lounge in the Z departure area, just in A (Schengen) and in B (not used by UA nor LH for USA departures).