Has a proto-language ever been accurately constructed prior to discovery of a historical text in said proto-language?

Vote #1, Daniel Ross: Daniel Ross’ answer to Has a proto-language ever been accurately constructed prior to discovery of a historical text in said proto-language?

Vote #2, Brian Collins: Brian Collins’ answer to Has a proto-language ever been accurately constructed prior to discovery of a historical text in said proto-language?

I’ll add that Linear B is similar to Hittite: it is closer to proto-Greek than anything we had, and it was deciphered after proto-Greek (and proto-Indo-European) was reconstructed. It has the digammas of proto-Greek, and it was the labiovelars of proto-Greek…

… except, it’s actually the other way around. If we didn’t have proto-Greek as a guide, we wouldn’t have been able to decipher Linear B. The syllabary was utterly unknown to us, and we have no independent corroboration, save for the odd pictograph that cracked the puzzle (tiripode = tripod). So it’s not like Linear B was as much of an independent corroboration of proto-Greek as we might like.