Entity Reference auto complete term creation on the fly?
Instead you can give a try to this Autocomplete Deluxe module to achieve your goal. It have the option to create new term in auto-complete field.


  Features

Combo/Select box like selecting.
Select without entering something.
Widget for taxaonomy
Chosen like multiple selecting.






  If you want to deny adding new terms, then checkout Chosen. It
  converts select boxes to autocomplete fields.