I'm reading the Rosenzweig book on Mahler (interesting). He amplifies Alma's claim that Mahler had performed all nine Bruckner symphonies in the U.S. Knud Martner's extremely precise "Mahler's Concerts" book makes no mention of this. Instead, Mahler conducted both the "Te Deum" and fourth symphony on three different occasions each, and the fifth and sixth symphonies just one time (each) in Vienna. Mahler was quite fond of the Te Deum.
As we now know, Mahler performed these symphonies in versions that would not be considered to be 'authentic' these days, and with his own cuts added in addition. But before we get too 'uppity' about that issue, it must be known that the printing of Bruckner's works was in an extremely messy state. It was nearly impossible to obtain the different scores in order to compare the different versions. It wasn't that easy to even acquire the parts. This is where Mahler stepped in to lend a hand.
As Mahler was beginning to get the printing of his own works transferred over to what is now known as Universal Edition, he pressured Universal to do the right thing for Bruckner as well. Given the high expense of making the plates for - and printing of - Mahler's works, Universal proposed that Mahler forgo ALL royalties from Universal until the 50,000 crowns it would cost to print Bruckner's works could be recouped. Mahler graciously accepted this proposal; thus, he actually did pay for the printing of a first, unified edition of Bruckner's works. However, this was 1909 or 1910, so it was actually Alma and her surviving daughter who would miss out on the additional 50,000 crowns (or whatever the currency was).
Going back to the fantasy that Mahler had performed Bruckner symphonies 1-9 in the U.S., is it possible that Mahler had rehearsed some of them but didn't perform them? I think even that possibility is a stretch, given the state Mahler's health at that time, and the fact that his relationship with his two orchestras in the U.S. wasn't always warm and cordial. We all know that Alma was often times inaccurate, and was prone to exaggerate things. But how could she be SO WRONG about something as big and important as a possible first performance of the Bruckner canon in America?
All accurate input welcome (and let's not just beat up on Alma - that's been done).