It’s an interesting thought-experiment, but it wouldn’t be possible practically. Why? Because of the limited scope of the corpus. Anyone who knows Pali well enough to translate into it—which is a lot harder than translating from it—is already very familiar with the passages and terms of phrase. So when seeing a translation, they’d immediately recognize the underlying Pali idioms.
That is, incidentally, how I manage to “read” or at least get some idea of, Chinese Buddhist texts. All the subtleties and nuance escapes me, but at least I can recognize what the underlying Indic phrase was in most cases.