"Trombone sounds more like a tuba."

I can't be sure because I'm not there with you , but in over 30 years of teaching and selling keyboards and organs, my guess is that you will need to play it an octave higher.

That was almost always the fix for my students and customers who didn't like a particular instrument.

I'd be curious to find out if that helped the issue with that or any of the other instruments you weren't thrilled with.

Best
Scott