I would not interpret local differences without a large library of sounds from multiple localities. I know how incredibly variable are calls of Tawny Owls. I heard a variety of muffled and garbled songs, half-finished songs and sounds in between the usual call and the hooting song. This spring I heard a bird calling for long time with a disyllabic hoot, which sounded like the start of a normal song without the main part. I see no reason why in North Africa there should be no similar variation.
Of, course, there might be an undiscovered cryptic
Strix owl breeding in Switzerland.