@userninenine no need to use volcalizer_ e2.tts_1.x.apk because that application was made from old Nuance.APK and libraries from other applications.
Nuance has encrypted *.HDR file so their new engines can not even read volcalizer_ e2.tts_1.x.apk and SmartVoices . They can only work with libraries written for PC.
But the problem will arise if the HDR for PC is encoded. Then the applications are unusable.

Code Factory Vocalizer 3.1.2 the application is much more advanced and better. It has a vocabulary, emoticon, and other functions. Supports the latest engines v3. I hope I've removed your doubts and you'll enjoy the Code Factory Vocalizer application.