Not many conductors have recorded the completed Finale of Bruckner’s Symphony No. 9, yet Gerd Schaller has recordings of it in three different versions, in August 2010, July 2016 and July 2018 respectively. In the first one he used the completion by William Carragan, and in the remaining two the completion by himself, with the last one a revised version of his earlier attempt at the completion. One will be interested to know what Schaller has revised in such a short interval of some two years. The main difference, among other minor ones, is in the apotheosis of the coda. In the first version, Schaller combined music from the 4th to 8th Symphonies and from the Helgoland and Te Deum with music from the first three movements of the Ninth. In the revised version, he changed his mind and “refrained from making direct allusions to other symphonies by Bruckner, mainly because there is no firm evidence to suggest that Bruckner himself planned such citations in the apotheosis of the finale”. Instead he combined the Te Deum motif with the Schlussgrupe chorale and a modified form of the main theme of the opening movement, and towards the end he wrote a triumphant motif in the trumpets and woodwind. Which is more convincing? I’ll leave it to you to judge.
The coda is everyone’s guess, no matter how educated a guess it is. No one can claim how authentic a particular attempted completion of the coda is. Put it bluntly, it just depends on the listener’s taste and predilection.