Some non-ASCII chars are ignored.

[cshaa]

If I use piper directly, it works as expected:

echo "Řekni řeřicha!" | piper -m cs_CZ-jirka-medium -f piper-output.mp4

piper-output.mp4

(You have to manually unmute the audio)

However, if I give the same text to speechd, it completely skips all the "ř"!

spd-say "Řekni řeřicha!"

spd-output.mp4

(You have to manually unmute the video)

Out of all the Czech diacritics áčďéíňóřšťúůý, only those with acute (áéíóúý) seem to be pronounced, the rest is skipped.