But then how do you explain the strong isoglosses with the pre-Latin substrate in Romanian and the prevalence of Eastern Romance over Western Romance (Italo-Dalmarian) borrowings into old Albanian? Doesn't that indicate that Albanian was either spoken or also and relevantly spoken to the east/northeast of Albania, and that those eastern/northeastern Proto-Albanian dialects were pretty influential in the development of the later dialects that survived to form the Gheg and Tosk dialects of modern Albanian? Also considering other toponyms and their phonetic evolution, I'd say the core of the Proto-Romanian Romance was originally spoken more to the west (towards/in Serbia), and the reach of Proto-Albanian included much ofthe present northern half of North Macedonia and the southern half of Serbia, encompassing all of Kosovo and extending to central-northern Albania. That geographic location would fit the particular division of Romance borrowings (western vs. eastern), the relative paucity of Albanian loanwords in Greek, the prevalence of Romance over Hellenic borrowings (for that would put most of the Proto-Albanian territory solidly in the Latin-speaking part of the Balkans), and so on.
I think I'm mostly agreeing with you about the core area, just maybe a bit more west and south.
There are a couple of issues where I'm not as sure or disagree.
Firstly, Albanian has a lot of latin loanwords, but we don't know what percentage of latin loanwords may have replaced greek loanwords from the previous period.
Secondly, the Roman empire was also different in its intensity and nature to Greek colonization, Greeks did not have as far a wide and brutally encompassing linguistic assimilation effect as the Romans did, and their expansions happened in different technological ages which determined or limited scope of linguistic influence imo.
Thirdly, i think the Jiricek line is a partially flawed or incomplete idea that has had an overall negative effect with respect to placing Alb in my opinion:
During the Roman Empire, Latin had more hegemonic power both north and south of the jiricek line, it wasnt a symmetrical relationship between Greek and Latin as if there was a parallel Greek empire during the Roman one. There are many towns south of the jiricek line for example where all administrative epigraphy etc is wholly in latin, and also many entire language groups that were entirely latinized, absorbed by latin, south of the jiricek line (vlach groups in greece, thrace, etc).
This attests to a more nuanced reality and not the reduced and simplified one that albanian must have been well "above the jiricek line" to have latin influence as is usually argued. I obviously still don't think it was super south, but i do think proto-albanian most probably was at least in north epirus, at the most in south epirus peripherally also. I sincerely am not motivated in this belief by any sort of nationalist ambitions, i just don't think the bronze age branches of l283, ev13, in southern albanians, especially the south west labs, are from a migration from the east. They match arber/komani culture finds, and suggest some sort of enclave also in the laberia region. I also don't see it feasible that laberia, the most compact tosk zone, was a latinized or greek speaking region until some migration from 6th century ad of proto-albanians. If i hear a decent argument for this then I will change my mind, but L283 branches in laberia are ancient.
We need to recognize that these reconstructions are in themselves quite volatile and privy to easily being skewed, especially with an incomplete ancient corpus like proto-albanian. So the question of the Komani/Arber culture, also called the Komani-Kruja culture has to be primary in adressing origin of Albanian since this is the region which gave Albanians their ethnonym. If this archaeological culture was not proto-Albanian, then why is it where we find the most non-latin, non-slavic, non-greek, Albanian placenames? There needs to be an answer for that. If it was a latinised illyrian population, it should be full of latin placenames. Positing non-Albanian komani-kruja culture is imo the most improbable argument atm. Kruja in itself is considered the earliest Proto-Albanian gloss, attested in 879, from Albanian. Kroi (spring, stream).
So before arguing about East vs West Romance stratums, we should keep in mind that maybe we don't actually know just quite well the sphere of influence eastern vs western dialects, and how it was striated across territories, classes, etc. Its probably not as simple as just a border line.
I think North-East Albanian dialects from non-Romanised Dardanians which are mentioned in Kosova by romans until fairly late. I think Vlachs of timok and south serbia are partially romanised Dardanians, Moesians (some are also just slavs or others which joined vlachs at later periods).