I try to describe what happened to me:
for a long time I used b4a 5.50,
compiled the code with targetsdkversion = 14,
and installed on an android 6.0.1 device,
the apps with the TTS library worked well, without problems.
Recently I purchased a new mobile phone with android 9,
I installed the new b4a 9.80,
recompiling the code with targetsdkversion = 14,
the apps work but the TTS features don't work (and the warning appears: 'the app is developed for an older version of android...').
I tried to set targetsdkversion higher but TTS don't work.
Putting targetsdkversion greater than 21 in addition to TTS features other feature of the apps also don't work.
I don't have the skills to understand what happens and to know what settings I need to do...