Some time ago I uploaded a voice file that enables the use of any TTS voice used on the Android system in Primo.
Simply check my latest threads to find it.
But I noticed that depending on the Android version and other mods the internal TTS system is messed up in other applications or mot usable at all.
Also some devices use a modified Android system that can cause problems in rare cases.
After testing quite a few voices I noticed that my tablet was pretty much messed up with the TTS system:
The Ebook reader would no longer read aloud, other programs refuse to use the vocie selected int he system settings and so on.
After deleting all TTS stuff and only using one system (Ivona) on top of what comes with the tablet all works fine.
If in doubt and only if you can afford the trouble use a good backup solution and a factory reset so you only install one TTS system to test.
One other thing to mention is that these "test versions" of voices often tell you they expired in their settings but you won't see anyting like that when using the voice in othe programs.