{I} should be pronounced /ɪ/, but it sounds like /i/ in some recordings. I noticed this in audio_bif.mp3 and audio_bir.mp3 - it's particularly conspicuous in {bIr} which sounds like "beer". These assets should probably be re-recorded. It's possible that other recordings have the same issue, though I haven't noticed it yet anywhere else; for example, it sounds just fine in audio_xi0.mp3.
Currently, the TTS just "coughs" whenever it cannot produce a sound. This is very confusing to new users, especially when they are looking up newer words in {boQwI'} which have sounds that have not been recorded yet. Another source of confusion is when users send non-Klingon (typically English) text to the TTS, in which case all it does is cough.
The TTS should pre-process the input and just say an error message when the input contains any sound it cannot produce.