Personally, I consider no English (or any other language , for that matter) translation entirely "valid," in the sense that I do not believe any accurately convey to a 100% certainty, in every instance of a word and/or phrase, the exact sense of the Hebrew and/or Chaldee/Aramaic, and/or Greek languages, as the writers were inspired to pen down the "God-breathed-out" words of Scripture. And this is despite the best intentions and attempts of translators, FTR.
Therefore, this is not an indictment against any version or translation, per se, but simply an acknowledgment that no two languages are identical, a primary Biblical case in point, the Hebrew vs. Greek renderings of the three vs. two identifications of God and Lord. The Hebrew word(s) [El/Elohim (God)] generally render fairly straightforward into the Greek word [God (theos)] from the Hebrew. However the Hebrew word(s) [Yah/Yahweh (often rendered LORD, in English)] by contrast to another word(s) [Adon/Adonai (Lord)] proves a bit more problematic, and a single Greek word [Kurios (Lord)] has to do "double duty", as it were, without fully expressing the OT differences. This is clearly shown in Matt. 22: 42-45, where, although we can figure out this reference, to Ps. 110:1, benefited by the translators, the Greek word is the same- kurios.
This is even more apparent in English. Not all idioms accurately translate, verbatim; NT (at least) verb tenses are 'clouded,' voices are 'silenced,' moods are 'hidden,' and/or any and all the above are non-existent, from one language to another, in some instances, without "adding to" (or "taking away from") Scripture, in order to provide the sense.
Over against that, I consider any and all translations as "valid" where the accurate sense of the language is conveyed in a word or phrase. That even extends to versions I have little to no use for, on any regular basis, generally preferring all "formal equivalence" versions. Yet I have no hesitancy to cite such varied versions as GNB, MSG, D-R, Liv., NWT, etc., when they happen to be appropriate, and do so, for in those instances, I consider them to be fully valid, even though overall, I would definitely consider them far less valid, than some others. I actually recall one instance where the MSG was one of only two (easily accessible, to me) versions that accurately expressed the Greek language (don't remember the verse or the other version, now), where no 'major' "formal equivalence" version did the same, much to my own surprise.
Ed