Audition Advice
Forgive the silly question, perhaps, but are you talking 50 bpm for the dotted half note, meaning each measure at 50 bpm?
That's a pretty healthy tempo, I'd say.
On the other hand, if you're talking 50 bpm of the quarter note, that's excrutiatingly slow -- it's good to practice at that tempo to get clarity and develop muscle memory, but the piece is supposed to be played at around dotted half note = 60 bpm or so. A bit slower would not be wrong.
Need more information to answer your question properly, but practice till you're sick of the piece and then practice some more.
I'm working (again) on COV and I have a lot of work to do....
U.S. Army, Retired (built mid-1950s)
Adams E2 Euph (built 2017)
Boosey & Co. Imperial Euph (built 1941)
Edwards B454 Bass Trombone (built 2012)
Boosey & Hawkes Imperial Eb tuba (built 1958)
Kanstul 33-T lBBb tuba (built 2010)