Hi Ken,
I get the same failure, and found that there was a release in 2023

github  com/rhasspy/piper/releases/tag/2023.11.14-2

I put the downloaded piper directory in /opt, along with the piper-voices/en directory and have a successful voice output.

uname -r                                                                                                                   

6.9.5-200.fc40.x86_64

[piper] [info] Loaded voice in 0.33 second(s)
[piper] [info] Initialized piper
Output directory: /home/mark/./1721984513770506807.wav