Learn what that means, and much of the difficulty fades away. Still, it's typologically non IE with few cognates, so it's a rough row to hoe. Did my most of my grad syntax papers based on data from Basque speaker consultants.
Don't like that the reporter botched "Proto-" with "Common". A protolanguage is an abstract construct based upon sound correspondences, possibly supported by language-change universals. A common language is the language used by a community of speakers prior to language change separating dialects into different languages (with the boundary between those two being a vexed nuisance). Those are distinct from "earlier form of the language," used when a language didn't break apart but merely changed.
I had to learn Common Slavic, kin to Common Slavic. But Proto-Slavic is both ageless and placeless (based on data and reconstructions, not speakers in a time and place). Common Slavic had dialects spoken in distinct locales--Kiev Blaetter in Glagolitic, canonical OCS texts in traditional Cyrillic. And I had to learn Old Russian, Primary Chronicle through Zadonshchina, and OCS and OR differed. These are real distinctions.
At best, Vasconce is Old Basque, but it requires tweaking what "old" means. Perhaps "Early Old Basque." There's only one Basque with various dialects. We can (and some have) reconstructed Proto-Basque, but it's likely nobody spoke it. The data set is partial and biased--just what survived to the present, plus historical attestations (however interpreted), and so the reconstruction is partial and biased, meaning "wrong". Pamplona "early old basque" would have been Old Basque with a twang, a dialect, unless the language had recently spread (even if that meant an influx of "economic refugees" because of Pamplona's economy.
Historical linguistics.
Henning ... Jakobson wasn't wrong.
= new reply since forum marked as read