Accounting for either thing is just as dumb. Attendance is dumb because it doesn't account for the same competition/markets, streaming at its peak, length of a theatrical window etc.Is marketable what we care about? Reason I went for attendance is a ticket sold is a ticket sold, regardless of format and I didn't want people saying exactly what you're saying, being that it got a lot of money from 3D showings. Premium formats are a lot more common now than they were in Avatar's time anyway, which is why I didn't bother mentioning that aspect.
Endgame will never beat Avatar when it comes to attendance, and that's a fact.
Regardless, I don't see why people seem to care if Endgame beats Avatar so much, like they have some personal stake in it. Disney wins either way.
Accounting for just 3D is dumb. Accounting for just modern China market numbers is dumb. Accounting for exchange rates is dumb. Account for inflation is dumb.
Stop trying to account for one thing over another and stop trying to do the impossible that can't logically be done.