I tried this with the original comment in the thread. Guaranteed to not be in the corpus, references a few terms that also wouldn't be in the corpus (Claude Fable), and long enough to be more than a sentence or two while short enough to compare in a discussion like this.

I did this with entirely local models I have sitting around on my laptop. Minimax M2.7 at a 3 bit quant with 8 bit quantized KV cache for English -> French, Gemma 4 31B QAT (4 bit quant) MTP for French -> English.

It's perfectly readable, but there are a few places where the phrasing is a bit more awkward after the double translation ("auditing" to "revision" in particular is a bit off). Gemma did comment on not knowing what Claude Fable was in its thought process: "The author compares Ellsworth's translation with one produced by "Claude Fable" (likely a misspelling of "Claude" or a specific version of Claude)."

Here's the double translation:

"I have no doubt that a writer is better at translating than AI, but I must say that AI translation has become so good that I'm not sure how much longer the profession of translation will exist—or rather, it may become more a matter of revision.

"For example, I just read Lawrence Ellsworth's translation of The Three Musketeers, which I enjoyed immensely. I neither speak nor read French, but from what I understand, Ellsworth's translation is considered one of the most faithful translations of the work.

"Out of curiosity, I asked Claude Fable to translate the original French version of The Three Musketeers; I asked it to translate faithfully, but also to try to maintain the same playful tone as the original and to censor nothing.

"Once it was finished, I didn't read the entire result, but I compared a few individual chapters between Ellsworth's translation and Fable's.

"They were honestly remarkably similar. As far as I can tell, nothing was substantially different between Ellsworth's translation and Fable's. I think the prose in Ellsworth's translation was slightly better, but Fable's was actually perfectly readable. Again, I don't speak French, so I can't say for certain, but I don't believe I would have had a significantly different experience if I had read Fable's version instead of Ellsworth's.

"It is possible (and probable) that this is partly a self-fulfilling prophecy; Fable may have been trained using Ellsworth's translation and can therefore draw directly from it. Unfortunately, since I don't speak any language other than English, there is a sort of vicious circle: the only way to compare the fidelity of a translation is to compare it to other translations, but if other translations already exist, that will likely influence the results, and if a translation doesn't exist yet, I have no way of verifying it.

"I am going to continue reading Ellsworth's translations for the following stories simply because it feels more canonical to me, and as I said, I think the prose was slightly better."