Clearly, you are not understanding what
@Kiyoteru has posted.
The voicebank you are using is Teto's CV - consonant vowel - library. The library has VV - vowel vowel - combinations.
The reason the Lyric Diphonizer is not working is because its purpose is to make the UST compatible with VCV - vowel consonant vowel. The bank you are using is not made in VCV format.
CV banks are aliased like so...
[か] [き] [く] [け] [こ]
Vowels in CV banks are usually just [あ] [い] [う] [え] [お] [ん] but vowel combinations may be added to facilitate smoother transitions and reduce CV's choppy nature. Vowel combinations are aliased as such [a い] [i あ] etc.
VCV libraries are aliased like so...
[- か] [a か] [- あ] [a あ]
CVVC libraries are aliased like so...
[- か] [a k] [か] [- あ] [あ] [a あ]
You can check a library's aliasing system by left clicking a note that isn't working properly and Ctrl+G. You will get the configuration window which will display the aliases the library has. The aliases have to match the lyrics or else they will not play.
Do as
@Kiyoteru instructed and download the library labeled as Triphone (VCV). That library will work with the Lyric Diphonizer.