I read before about this here
My users are complain about the translation result by google most of them are very bad or not correct, we must be can manually editing the result/chace with better human translation for some posts
So as google translate tos, we cant modify and save the translation result/chache like you said in bold above, but we can translate the post 100% manual that need better human translation in that post, so nothing google translation in the post that edited by human translation
For example i have a single post that very bad result in other language with google translate, so admin can translate that single post, manual 100% and save the result without needed cleaned it latter
hmm i am still thinking how to do this with current vbet version now using phpmyadmin or manual in the post