My Function eating out part of the code

[hardy trench]

local function PianoTerra(sound)
  if sound then
    sound:Play()
  end
  -rest of the code-
end
PianoTerra(sound) --// with 
PianoTerra() --// without

could always add a parameter to the function and add a conditional check
if you want it to play a sound pass the soundID into the function
if not then it'll just continue as usual

also if you put all the children with ClickDetector under one folder you can just use one chunk of code for everything instead of making a line for each instance

local Folder = game.Workspace["Folder"]
for _,v in Folder:GetChildren() do
  v.ClickDetector.MouseClick:Connect(PianoTerra)
  end)
end

local Folder = game.Workspace["Folder"]
for _,v in Folder:GetChildren() do
  v.ClickDetector.MouseClick:Connect(function()
    if v:FindFirstChild("Sound") then --// replace "Sound" with sound name
      PianoTerra(v:FindFirstChild("Sound").ID) --// not sure what the ID property is named under sound instance
    else
      PianoTerra()
    end  
  end)
end

by putting everything under a folder and adding a sound under each of the parts you want to play a sound when clicked you can also just do this