I would love to see a German MP 28/II with 20 rounds at BR2 it would be a good counter to the Thompson. This would make a great event weapon or event squad. The MP28/II is one of the few guns not in the game and the 45 cal is something the Germans lack. The gun would be very powerful at br2 and
round out the German arsenal.
Im not a 100% sure about the Mp28/II in .45 acp having 20 and 30 rounds mags because it seems to be a rare mostly unknown variant and so its rarely mentioned in books.
However the better documented Mp34 in .45 acp had only 20 round mags, so itβs likely that the Mp28 in .45 also only had 1 magazine which is the case according to Gun wiki (same source you gave).