I live in Paris and am AA EXP but am no apologist. Hysteria can only exacerbate sensitive situations and I suspect that's what happened here.

CDG is no worse (or better) for US-bound departures than Germany, AMS, etc. For traveling within Europe it's remarkably efficient.

"AA security personnel" are AA employees. They are driven to ask what they do by the DHS. This year after an invasive new line of questioning made me "refuse to answer based on privacy", I was pulled aside and chastised with "she's just trying to do her job" by the "head of AA security". I replied "these new questions aren't very French", and he responded that the TSA was actively "doing training and observation" and that "he completely understood my concern".

AA must have picked up on something that they wanted to follow-up with. Repeated questioning can happen; and if you get SSSS'ed you will get a deeper search tailored to DHS rules.

By challenging duty free purchases (liquor is wrapped and sealed in plastic bags) on a plane; you are immediately escalating the situation and must be prepared for a follow-up.

Any airport security is sensitive to being called out as to "jeopardize our security for the sake of profit". I suspect you were respectfully but firmly handled. I imagine that other EU countries might have even been more "hands on".