Hi there - yes, unfortunately the project would need to be restarted for the change to take place and the restart may take up to 12 hours to happen - it wouldn’t take down the site for an additional 12 hours. If you let me know the name of your project I can do it manually for you right now.
When you update the version of Node, it doesn’t register until the container restarts or falls asleep. Most projects fall asleep after several minutes of inactivity - once they wake up they will have registered the new version of Node you chose. But boosted projects do not fall asleep with inactivity - they do restart around every 12 hours, which is where that maximum came from.