Word for "translating" English to English

I would describe the process of transforming a text written in a source language (e.g. Old English) that is largely unintelligible to readers of the target language (in this example, modern English) as translation.

Adaptation could refer either to the transformation of the work from one medium or format into another (e.g. the transformation of a novel into a screenplay), or to the rewriting of a text for a different audience (e.g. the simplification of a story first written for adults in order to make it easier for children to read).

Turning an archaic or old-fashioned text that is still largely intelligible in its original form into contemporary language is modernization or updating -- though the term revision has also been applied to modernized versions of the Bible in particular.

In my opinion, modernization would be the most appropriate term to describe the updating of the English of a text written by John Locke into modern English.

To render Text A into Text B is a general term that could be applied to any of these transformations (as too is the verb transform, of course).