If this is what we want… sounds fine to me, even though it means
that a meeting of 4 people can cause change of bylaws, if 3 people
agree. However, we cannot guard against all malice anyway.
We could add a safeguard that there's a grace period of two weeks after such a decision. If more than 50% of active/honorary members object, in writing, within that time, the decision is reversed.
This is a corner case, though.
The only other thing I see as of right now is that extraordinary votes go through the board or a board-designated proxy. I would prefer to have that run through someone external, like the Debian secretary, to avoid potential abuse by the board. Also a corner case, but slightly more realistic, imo. And I say that as someone who intends to run for board (unless there's already a strong candidate pool for the board, I guess). Also see da569cf00705df82ade627d1bcb793d49f75a8d6 in Git.
Text like "einer den Mitgliedern des Vereins vertrauenswuerdigen Person" might fit the bill, here.
Again, I am very happy with our current state,
mainly thanks to madduck for driving this, Richard