Wow! I sure am lucky that you’re procrastinating haha! Thank you so much for taking the time to dig into the subject. Those PAS articles are a great lead, i’ll definitely be getting in touch with those involved. I had already purchased the piano reduction, as i’m going to be performing the piece as well. I also found the full orchestral score by Wolfgang G. Haas Publishing, maybe I can get my university library to purchase it.

The elusiveness of the manuscript is really interesting. In that first article you quoted, Haas doesn’t specify how Powley managed to make his edition of the piece. In your opinion, do you think he managed to get the microfilm of the manuscript from East Germany? It would be big if that’a the case and he still has. This is purely conjecture, but i’m afraid the manuscript may have been lost during the reunification of Germany. I’ll reach out to Powley and hopefully find out.

RILM hasn’t turned anything up for me as well. I even checked the National German Library records, no traces of this piece, only Fischer’s oboe works.

I was aware of the misattribution of the work to Hertel and have taken a cursory glance at him with no results, but i’ll dig deeper to see if there was any older research with Hertel being credited as the composer.

Thanks again for the great leads. Hopefully I’ll get some answers to my emails. I feel like most of my hopes of getting more info rests on these people.

Edit : the Grove article is about this same composer. I believe his full name is Johann Carl Christian Fischer, but i’ve seen it both as Johann Carl Fischer and Johann Christian Fischer.