You cannot, in general, use /e/OS as a method to downgrade Android OS version. There is an explanation in this post Can I downgrade Xperia tablet Z2 Castor from LOS 18.1 to /e/ q? - #8 by piero.
You cannot, in general, use /e/OS as a method to downgrade Android OS version. There is an explanation in this post Can I downgrade Xperia tablet Z2 Castor from LOS 18.1 to /e/ q? - #8 by piero.