This is NOT a true passive verbal sentence, but a mere copulative adjectival one, as the past participle is used like any descriptive adjective. “Riddled with” one may approximately replace with “full of”. It is NOT the symmetrical counterpart of “Orwell riddles his work with so many passive verbs”, in the sense of “is riddling”, or “keeps on riddling”. In German the distinction between passive verbal clauses and adjectival ones is far neater, thanks to the specific auxiliary “werden” (“becoming”, “getting” )used to form passives (colloquial English often uses “is getting done” in that pure passive sense, probably for being closer to vernacular germanic and Scandinavian roots, while the more learned aspect of English rather emulates romance languages in the formation of passives using the “be” auxiliary in a very specific sense that is not merely copulative), whereas participles used like any qualificative adjectives to describe a quality or a state are used with the auxiliary “sein” (“be”). In a true passive sentence like “the text is glutted translation after translation with redundant expressions as the original is no longer referred to”, the passive may be replaced by the use of “one” or “they” : “they glut the text with redundant expression translation after translation as they no longer refer to the original” : it amounts to the description of a process the author of which remains indefinite or put in relative background, which does deprive the sentence of much its expressive force under the typically bureaucratic reflex to hide inconvenient things and responsibilities under the veil of official anonymousness (it must be noted that Russian vernacular as well as the official language resort equally to passive or quasi-passive impersonal forms in all situations owing to the fatalistic character of the culture where weather and government decisions seem to issue from the same realms). Therefore the rule of the thumb implied by Orwell should be to restrict the use of passives with the same force good communicators also avoid to use too many “one”’s or “they”’s as excessively non-committal and not so clear-thinking people like to sprinkle their speech with. But when one writes “the text is glutted with redundant expressions owing to too many translations” one cannot write as an equivalent “they glut the text with redundant expressions owing to too many translations” which comes out quite meaningless, therefore it is not a true passive, and it doesn’t fall under Orwell’s cautionary remark.
