You can’t disqualify Illyrians because of the DNA relationship.
Grouping them with westerners is just another myth. One only needs to look at their Y linages, especially southern Illyrians (Illyrii proprie dicti) - same linages that also Mycenaeans had.
That's a pretty weak line of reasoning on a couple of fronts.
How and why we share those features with Baltic linguistically, could be anything.
That’s why ancient DNA is so popular today because linguistics proved to be inconclusive.
Actually, exactly the region where IE came from was correctly pinpointed with linguistic analysis 160 years ago.
Theodor Benfey in 1868 argued exactly for the steppe region between the Black Sea and the Caspian Sea as the IE homeland based on linguistic analysis of shared vocabulary for animal species, plant species, and geography, that all matched the steppe.
Looking back 160 years ago we can see that he was exactly right, there was nothing inconclusive about it.
The fact that some linguists and schools of thought had different arguments, either due to ideological/nationalistic motivations or sheer mediocrity/incompetence doesn't make it "inconclusive" as a science, since that exists and will always exist, in DNA too.
Many other linguists over the years argued exactly the same region as him, Marija Gimbutas being another famous example in 1956.
The case is identical with Albanian, in 1878 the Romanian linguist August Bogdan Hasdeu argued that the Albanian language descended from a branch of Dacian that survived south of the Danube.
He based this on linguistic fact, namely that Albanian and Romanian have a shared non-latin vocabulary, mainly related to pastoral/transhumance terms. (Of course the lexicon in Albanian pertaining to transhumance shepherding is the most pure Albanian, inherited from the original Yamanaya days and not loaned from other language groups, so it is most likely also the core group least likely to be mixed also genetically, so this again has great implications against the western balkan yamnaya as source of Albanian language.)
Often referred to as a substrate, today some prefer to call them loans from proto-Albanians rather than a substrate language of Romanians, but whichever position you hold, it necessitates proto-Albanians either being neighbours in intense contacts with Romanians, or the pre-Latinised core of Romanians speaking a proto-albanian dialect.
Why the relation of Albanian to Romanian disqualifies the west balkan yamnaya groups from being the source of the Albanian language is not just the "Eastern Latin" that you refer to, but also the non-Latin Albanian component in Romanian. It requires proto-Albanians in the areas of the Romanian ethnogenesis.
Even if there wasn't an Albanian substrate component, and it was just the Eastern Latin, it still could not be explained by illyrian speakers accepting eastern latin speaking EV13 migrants, that scenario you propose makes no sense linguistically. Albanian is internally consistent, and the soundlaws and different chronologies that we can observe in Albanian layers of vocabulary show us that the same sound laws that operated on the Eastern Latin layer of vocabulary also affected the inherited lexicon from PIE. Therefore we know that these Eastern Latin speakers must have been the proto-Albanians that also got their language from PIE.
Long story short, it wasnt Illyrians in Mat that are the source of proto-Albanian
Likewise the shtokavian dialects are less albanoid lexically and grammatically than bulgaro-Macedonian, which points to west balkan being a non Albanoid language for slavs to interact with. All these things have been mentioned in this thread countless times.
So the problem is that there is nothing inconclusive about linguistics, and the linguistic facts against west balkan being the theatre of proto-Albanian hold strong.
It's been known since 1878 that Albanian linguistically cannot be from the western balkans, and countless other linguists since then like weigand, jokl, bonfante, russu, georgiev, rusakov, matzinger, have also added to the proofs of this.
There is nothing inconclusive about all Albanian toponyms entering the Albanian lexicon aftet the roman invasion of the balkans, the phonological mismatch between Albanian and Illyrian toponyms, the Albanian-Romanian symbiosis, the Albanian-Baltic symbiosis, and countless other linguistic facts that disqualify Glasinac-Mati or any other western balkan yamnaya group being the source of Albanian, they are all settled.
