Changes to the world and player engagement
1.) Traveling bands and/or stages and podiums with example instruments that players can interact with and experiment with outside of their housing. This one has a lot of flexibility in it, and CT has tons of leeway with how they might implement it, but my favorite interpretations are stuff like:
a.) Traveling band NPCs that only appear during a certain time of day within the game, and depending on the day of the week go to different cities. Monday Detlas, Tuesday Llevigar, etc etc. They only play a few songs, and they are dependent on location. (you can buy the music sheet for one of the songs that you like but only if they are still there and you are within the correct location)
b.) Band NPCs that exist in multiple cities (do not travel or despawn) and each have a side quest associated with fixing their particular instruments. Completing it "teaches you" to use those instruments permanently like Recovering the Past with Ability Shards. They give you a free music sheet that is already filled out that corresponds to the instrument you fixed.
2.) Continuing off of point 1, having instruments that are placed in the world accessible to players. The range would only be about 4-5 block radius, but anyone within range can listen to you play (only one person per instrument) so that way you don't have to invite people to housing every single time you want to show them a song
3.) Portable instruments so that you can play custom songs on the go, and play songs for your party or random people you meet if you really want to. This would add an entirely new level of player engagement and creativity!