"Their proof" is I quoted 2 linguists saying the same thing
Istvan Schutz "The name of the Dalmatian/Delmata Illyrian tribe, Dalmatia/Delmatia area, the Illyrian city Delminium/Dalmion, and the name of the present-day Delvinë and Delvinaqi geographical units are related to the Albanian words dele (plural delme) 'sheep', delmer 'shepherd'. Strabo adds the epithet "...πεδιον μελωβοτον..." to the name of the Illyrian city Delmion, meaning "sheep-feeding plain"."
"Linguist Xhelal Ylli translates Delvinë as "white sheep"."
So now you admit a relation to other Illyrian tribes ? First you argued tribes outside Albania were supposedly not Illyrian despite there seems to be a connection even to Messapian, Dalmatian, Dardanian etc. We also have the ''Dardha'' tribe for example. Seems even a connection to the Hallstatt and Maykop.
'Arber', 'Arberia' etc comes from the name Albanoi, Arbanon etc. These names were used in the past, then Epirotarium came to be used or 'Epirote' , modern Albania was part of Roman Epirus and medieval Albanians referred to themselves as 'Epirote' , although it was never really inhabited by the actual Epirote tribe which was more South of the Shkumbin. It's kinda like how modern Northern Macedonia became named 'Macedonia' by the Romans. Interesting enough. I wonder if these names have historical connection which the Romans regarded ? Some say for example Roman Epirus in Albania had Greek influence at one point rather than Latin.
Origin of Albanians is in the Maykop culture. Barleti writes Albanians came from Colchis.
Barleti repeatedly stresses the national aspect of his work. Scanderbeg is not only an impressive hero, but also the saviour of his native country. When he is compared with Alexander the Great and Pyrrhus, these are not arbitrarily chosen models from antiquity, but national heroes, for Alexander's Macedonia and Pyrrhus' Epirus are for Barleti synonymous with his own country. Mostly he calls it Epirus, but also often Albania. In a digression early in the work he elucidates his view upon the history of the nation based on the Roman historiographer Pompeius Trogus and his own contemporary, Pope Pius. Thus, the Albanians originally lived in Colchis on the Black Sea, from where they brought their language. They first emigrated to the Albanian hills near Rome. When Hercules as one of his twelve tasks had killed Geryones and was driving the latter’s cattle from Spain through Italy, he stayed for a time in the Albanian hills. From there the Albanians followed him, and they now live in Macedonia and the Peloponnese.
http://scanderbeg.dk/Barleti-Scanderbeg.htm
Colchis was where Maykop was located and where J2b2-L283 was found. We came from Caucasus. All humans in Europe came from Caucasus. Even Serboi tribe are Caucasus.