I'm not really one for introductions, so I'll just list off the sounds I think MuseScore should have:
1) Mellow Trombone
The current trombone sound is loud and harsh. Great for loud, fast-paced marches, but terrible for a slow, quiet serenade. This is why a second trombone sound is clearly needed, but right now, if you want mellow, you're better off just using a euphonium. Which reminds me:
As a euphonium player, I take offense to the fact that the euphonium doesn't have its own sound. We have been under the tyranny of the tuba sound for too long, and now it's time for a change.
The range is also a problem. A professional on a fully compensating euphonium has the capacity to play a chromatic scale from F1 to A5. MuseScore euphoniums only have the capacity to play from E2 to C5, and that's a problem.
Also deserving its own sound, this Armenian instrument can make nearly any song sad. However, the clarinet, which is the sound the duduk uses on MuseScore, cannot. The proper sound of the duduk can be heard at https://mynoise.net/NoiseMachines/dudukSoundGenerator.php.
4) Eb Saxophones
This part isn't about adding sounds, it's about changing them. The alto and bari sax sounds are much like the trombone sound: loud and harsh. Except these aren't even realistic, they're just annoying to deal with. These instruments sound much sweeter in real life, as this video and this video clearly show.
5 French Horn 1 & 2
The plight of the french horn is a concerning one. It's to harsh to feature a solo in a serenade, but too mellow to have one in a march. I suggest splitting it in two.
Please leave a comment below saying what other sounds you would like!