Thank you for this review.
Seems there are still some honest guys respecting our work.
Customized than you text can be made with the advance version in a very easy way.
But we don't want to hide that you can also change the standard thankyou text in whatever you like.
It is not that convenient as for the advance version but you just need a text editor to change.
The frontend language files can be found in components/com_proforms/language.