That's difficult to say. The arrangements were made by Méav and partially Máiréad N, none of the original songs were written by him. So he was obviously not involved with the music.
However, I am almost certain that Éabha was cast by David and no one else. Also, I assume he never "left" CW, but just doesn't work on the group right now. So, he's officially still involved, but simply doing something else right now.
But Eabha's casting could've also been done by Meav too. After all, she was in Anuna and she also knows that David likes to pick from the Anuna pool.
As for the rest of it, yes I know of his other projects but, typically, soundtracks are recorded weeks before the show is filmed. So I was wondering more about whether or not he produced the album. I know he wasn't involved in the filming process.
Also, I am looking forward to Brett Pruneau's solo album if it's truly in the works! I LOVE his version of If You're Not The One!