I just wondering if it is possible to check if user have appropriate right to edit post content using particular CRED form.
If not, I would like to show some message or even redirect him
Please advice
If you add Access to your set-up then you can set rules for which roles have permission to use which CRED form (publish forms, edit forms, for either post or user forms).
If so then you can just use the toolset_access shortcode to wrap where you insert the CRED form.
You'll need to insert that twice, one to handle the case where they are allowed to use the form (insert the form), the other for when they are not (display a message instead).