I think I thought of a clever way to make a piano add on, somwthing everyone has wanted for a long time. I draw upon processes of other mods that could make this work.
The addon is just an item, an empty hand, that when clicks a brick, it enables the player to play music. This is how it works. First, on clicking a brick, it changes the player's datablock to no-move player, as used in camera events. Next, coding disables all keybinds, so as to make the keyboard into a piano keyboard, such as used in the restricted server mods, like toggleable lights and Slayer's no painting/building ability. Then, the coding keybinds pre-recorded tones to a series of keys, from S to K, and it acts as an emote when the key is pressed, such as the alarm emote (it would be good if the key could be held to elongate the note, and if emote spamming could be overridden). Once the player is done, he clicks the brick again to be changed back to his old datablock.
My other idea is to emulate a midi keyboard for blockland.
