You are correct for all tickets except the RTW products. I've done this before (not intentionally, the AA RTW desk just booked me on the AA codeshares whenever they existed, and I didn't care so I wound up with some strange AA codeshares). And of course with the EU all EU airlines have traffic rights between all EU countries (leading to the strange sight of a BA codeshare between Germany and Denmark, for example, now that BA has pulled out of its BA Deutschland venture). US airlines do have some special traffic rights in Europe (and Japan), a legacy of past times. I'm not sure about Romania/Bulgaria but it may well be that AA has traffic rights via LHR. As you say the point is moot without an agent, and soon the fares will get into sync one way or the other. I'm pretty sure the EUR denominated fares are what was intended.