Hallo
This is a Problem.

// Activate an event: if the blob hits something, a sound shall be played.
// We set the event function and the collision flag for triggering
// EVENT_FRICTION event at collisions with the level.
pXent_setcollisionflag(eBlob,NULL,NX_NOTIFY_ON_START_TOUCH);
eBlob.event = Plop;

Why only goes the event once?
olso with NX_NOTIFY_ON_TOUCH.
The Kollisionsevent stops after a time.
Is this a Bug?