Here are the updated headcanon voices for The Brothers Sweetnote, given the time skip.

Lance Sweetnote:
https://m.youtube.com/watch?v=Owmso-LDTos

Lambert Sweetnote:
https://m.youtube.com/watch?v=7DaFiR7K5-Y

Ryland Sweetnote:
https://m.youtube.com/watch?v=tfvG0TIE5js

Alfie Sweetnote:
https://m.youtube.com/watch?v=jLNrvmXboj8

So, what do you think of these voices?