... regarding G. E. M. Anscombe's translation and the need for a new edition, Hacker and Schulte offer the following in the 4th edition of Philosophical Investigations:

"Anscombe's translation was an impressive achievement. She invented an English Equivalent for Wittgenstein's distinctive, often colloquial, style. This was no mean feat. For she had to find not only English analogues of Wittgenstein's stylistic idiosyncracies, but also an English rhythm that would convey the character of Wittgenstein's carefully crafted prose. Her success is indisputable.

Nevertheless, there are errors of different kinds in ... [Philosophic Investigations]. It was because of these that the Wittgenstein editorial advisory committee agreed to the production of a new edition. But, given the excellence of the Anscombe translation, it was resolved that rather than making a completely new one, we should build on Anscombe's achievement and produce a modified translation, rectifying any errors or misjudgements we discerned in hers. It should be emphasized that many of the errors in the ... [older editions of PI] could not have been identified in the 1950s, prior to the availability and extensive study of the Wittgenstein Nachlass, some crucial items of which did not come to light until decades later."   (4th Edition PI, page viii). 

Dr. Sean Wilson, Esq.