For the catechism, how about relations boosts with HOL, HES and (maybe) SCO. These are the countries that are typically Calvinist, and that comes off about 90% of the time. I would definitely trigger it on being reformed - it doesn't make much sense for a Lutheran state.
Is there a Christian of Anhalt event? I think there ought to be as he was a very influential minister for the Palatinate.
As to German minors I think that interesting ones are Hesse (nurtured the reformation, was split into 4), Lorraine (with dynastic ties all over the place), Meclenburg (just because have that COT, I don't know anything too interesting about the history) and, of course, Bavaria (counter-reformation, various french alliances, gaining the electorate, and more).