On the few occasions I've seen this message I've meant to ask about its wording. The one is plainly a typo (surviving for many years). What about the other, about aspect ratio: a typo too? I see no way that a frame rate conflict can change the AR.
I think the typo "Adjust movie" should be "Customize movie" and not "Adjust export" as you suggest in your correction. There is a second reference to "Adjust export" that sounds valid, and the correctional action is more coherent with "Customize movie".
The other I guess is a consequence that the error box also is (primarily expected to be) used for an aspect ratio error.
Thanks. Agreed, I think I was wrong on the first point.
On the AR issue I’m not convinced. I interpret that sentence as starting with “Therefore objects may judder...”. Also, unlike the previous paragraph, there was no data presented about an AR conflict. In my test there was none.
Anyway, a decade or so overdue for a decent edit IMO!
I think the warning is there to draw attention to the fact that you have edited a movie in a certain format be it AR or FPS and have chosen a different format for the export which will make the result look different to what you have seen during the edit. Choosing a different AR could have consequences on things like how titles appear, not to mention the obvious change in dimensions of the frame, as much as added or missing frames.
IMO Adjust movie is correct as it is telling you to adjust the movie settings and play the timeline again to see how the movie will look in the different format you have chosen for the final product. I agree though that there should be some other reference to AR and it should say frame rate where you have corrected it.