No one knows what proto-Slavs spoke precisely we can only assume it is a Satem Scytho-Iranic influence. They migrated to South Central Balkans peacefully. They got excited through the potential of glory of being emperor of a millenia old succesful empire centuries after their christianization which enabled them to conduct commerce etc with their immediate neighbours. When you are on top everyone tries to take you down which is fair enough...they mingled with locals (they did not migrate to a barron waste land) but they did migrate some 750 years before anything about an Albanian was written.. possibly a combination of a south slavic settler and cuman/pecheneg yamnaya (this is albanians)