Thanks for your suggestion.
When you say "Tunnelblick often cuts off" I assume you mean that the VPN becomes disconnected even though you didn't tell Tunnelblick to disconnect.
That should not be happening. You should investigate what is making OpenVPN disconnect the VPN.
You can be notified when OpenVPN tells Tunnelblick that that has happened. Set up a sound to play when the VPN is unexpectedly disconnected. That setting is on the "Sounds" tab of Tunnelblick's "Advanced" settings window. If you change it, the change will be applied to all of the configurations that are selected on the left side of the "Configurations" tab of Tunnelblick's "VPN Details" window. Instead of a sound, you can have Tunnelblick say "ABC VPN has disconnected", where "ABC VPN" is the name of the configuration.
That said, I will look into adding a notification, too.