Hello,
I update texts:

_JOOMLACOMMENT_FORMVALIDATE_CAPTCHA,

_JOOMLACOMMENT_FORMVALIDATE_CAPTCHATXT,

_JOOMLACOMMENT_FORMVALIDATE_CAPTCHA_FAILED

which were missing in Czech translation. There are still keys which are not translated, but that are not so urgent for me... so, I let them untouchted.
Hope that it help somebody...

Have a nice day ((-:
Jan

PS: Very nice work Daniel, thanks you. czech.zip