CPO snuck this into the Presto New and Future Releases:
https://www.prestomusic.com/classical/products/9771897--georg-joseph-vogler-scala-symphony-overtures
Maybe CPO ought to set up Howard Griffiths and an orchestra in the IMSLP (International Music Score Library Project) with recording equipment - and say "have a go at it". (Unsungs of course)
Doesn't sound as if it really dates from 1799 - and not to my taste