Schumann - Symphony No. 3
General Advice
This is one of the most standard orchestral excerpts for trombone. Yes, I see the high Eb. You would be unlucky to be asked for this excerpt in a youth audition, but I have seen it come up nonetheless. Play this one soft, but not so soft that your sound loses its presence. Also, pay special attention to your intonation as you play in these softer dynamics. Finally, focus on very smooth note transitions and a fast slide. I recommend recording yourself and listening back to find areas for improvement.
Resources
Full Orchestra Excerpt Recording - Berliner Philharmoniker
Masterclass Breakdown with Thomas Leyendecker - Carnegie Hall
Trombone Section Recording - Ian Bousfield, Gabriele Marchetti, Beat Ryser Firmin