Having http://www.gamesas.com/topic/1513334-no-viable-alternative-at-input/ this script into Bendu's Goodbye info Papyrus box

MSQ01BenduGilfreBefore.Start()debug.messagebox("Scene start triggered")

the scene won't start and his other goodbye "I'll still be here" doesn't function.

Any clues?

I presume you've filled the properties? Does the messagebox pop up? Is this in the End Papyrus fragment of his goodbye?