I mean the Kingdom of Germany, as in the part of the HRE that did not belong to the Kingdoms of Burgundy, Bohemia or Italy. This is a distinction that did exist, as is demonstrated e.g. by the existence of the offices of archchancellors of Germany (Archbishop of Mainz), of Italy (Archbishop of Cologne) and of Burgundy (Archbishop of Trier). Also, the Imperial Reform initiated at the Diet of Worms in 1495 only applied to the Kingdoms of Germany and Burgundy, and not to Imperial Italy, Bohemia or Switzerland - which is why the Swiss cantons were not part of an Imperial Circle.
Since Italy, Bohemia and Burgundy are not part of the German region despite being part of the HRE, I daresay this is not too bad an argument against including Switzerland in the German region.