This is an area where people seem to understand different things from the words ”revision,” “editing,” “proofreading,” “checking,” “polishing,” “adapting,” “updating” and so on.
Let's try to clarify the subject a little bit.
Revision (bilingual editing) means checking the quality and completeness of a translation. Obviously, this is done with reference to the original! One important aspect is ensuring terminological accuracy and consistency.
Polishing (editing) refers to stylistic concerns. After a good polishing job, the translation should read as if it were written originally in the target language AND should be thoroughly suitable for its intended target audience. This is where adaptation comes in. It most often applies to a translation, but it’s also quite common to adapt “perfect” copy written in one flavour of a language (let’s say French from France) to another (Canadian French, for instance).
Proofreading and grammar checking (copy editing) means reading a translation done by another person, or copy written in just one language, to correct any grammatical, spelling and punctuation errors.
As a final step, proofreading typically does not require reference to the source text, if there is one. It should take considerably (up to 50%) less time than doing the actual translation, but in some cases, a job turns into revision or a even complete retranslation! It’s worth noting that translators usually prefer retranslating a machine-translated text from scratch to trying to proofread it—which of course improves translation accuracy.
Updating a translation means translating only the parts of the text which have changed in the original. Obviously, it should take considerably less time to just translate the changes than to translate the new text in full. But that’s if the changes are easy to spot. Translations of technical manuals are often updated, and version control is an major challenge in this area.