Very nice scriptlet.
Please note that not every instrument will sound the first note correctly after the plugin has been bypassed by the scriptlet.
The included plugin worked fine, as did Pianoteq, but Kontakt 7 had a slightly delayed attack to the first note played after bypass. IK’s Hammond B-3X and AAS’s Lounge Lizard did not respond at all to the first note played after being bypassed. By that I mean, the plugins came out of bypass, but there was no sound from the note being played.
Perhaps adding in a small degree of latency to the first Note On message being relayed after the plugin is in bypass could solve the issue?