Also i see the cause, in log file on startup it says

[21:08:53] [Client thread/WARN]: File enderzoo:sounds/owl/hootdouble.ogg does not exist, cannot add it to event enderzoo:owl.hootdouble
[21:08:53] [Client thread/WARN]: File enderzoo:sounds/owl/hootsingle.ogg does not exist, cannot add it to event enderzoo:owl.hootsingle

and they arent found because files are camelCase