I think that might be quite a challenge. The Rosetta Stone was a huge breakthrough find, as it was an important clue for hieroglyphs, as it had the same decree

I think that might be quite a challenge. The Rosetta Stone was a huge breakthrough find, as it was an important clue for hieroglyphs, as it had the same decree written 3 different times. Linguistic anthropologist s usually learn from many hours of field recorded conversations for nearly extinct languages. The Bible is the arguably most translated book in history. If the Bible has a translation in one of your dead languages, you could start there. Even Machine Learning needs language pairs (same text in two languages) to get started.