I've fixed the problem! The ccbGetClosestNode had incorrect parameters set in the behavior_Terrain_walkSurface,js script. I commented out the line below and replaced it to make it work with the updated APIV2 function:
// get fall collision node
if (this.using_water && collPos.y < water_height) {
collideNode = this.water_node;
}
//else {collideNode = ccbGetClosestNode(pos.x, playerY, pos.z, collPos.x, collPos.y-0.5, collPos.z);}
else {collideNode = ccbGetClosestNode(collPos.y);}