I was struck by this phrase in a book by Donald Davie, poet, critic, and translator. All his translations from the Polish, his book on a Polish poet, etc... All his strong opinions about other translators from the Polish... and yet he did not have a reading knowledge of Polish sufficient to have "recourse to the original." It looks like he did know Russian, but still, I find this astonishing.
Davie was not a half-assed guy, in general. In fact, he pretty much held translation up to an impossibly high standard. He could have learned Polish if he already knew Russian. Granted his book on Milosz is short, but I don't know of any other critical books on poets written by people who don't know the language.