Characters speak too fast, which sounds funny, but also annoying. Anyone else has this issue? If yes, is there a way to fix it?

I have found solution on my own. To fix speech rate and get rid of "looney toons" voices, you need to add -relax_audio_cap in shortcut's properties. For example:

C:\yourpathtosudeki\Sudeki.exe -relax_audio_cap

or

"C:\your path to sudeki\Sudeki.exe" -relax_audio_cap