My Typ D is also a reverse Tessar-derivative, and not a triplet.

I believe the "non-typ-D" fast Xenars are "normal Tessars", and can confirm that at least one Typ D is a reverse Tessar with negative power uncemented rear cell (two air-spaced lenses in the rear cell, a cemented pair in the front cell).

Until I see a Typ D triplet with my own eyes, I'm prepared to assume that the Vade Mecum is yet again in error when describing less common German lenses, and that all Typ D's are reverse Tessars. It wouldn't be the first such error.