The use of "themselves" in this context and in English sounds pretty artificial to me. The only situation where I could imagine the sentence would mean anything in English would be if the persons referred to relied on a computer or another method to speak German without actually having the knowledge to speak it without "external" help. The question is, is the use of "înşişi" natural in Romanian in this context? Is there the same implication in meaning as in English? Is it used to contrast with other people who do speak German?