An argument can be made that Spontaneous Divination alternate class feature qualifies.
Sure, as a recommended house rule.
Does the ability to spontaneously cast domain spells granted by the Domain Spontaneity feat (CD) fulfill the spell requirement of the reserve feats from CM?
Not technically. Since you don’t have a list of spells known, only a list of spells prepared and the ability to cast some spells spontaneously, having the ability to spontaneously cast domain spells that fulfill the requirements for reserve feats does not fulfill the reserve feat requirements. That said, there’s probably no harm in allowing it, and an unflinching DM confident in his ability to challenge you at every turn can have no problem hand-waving the technicality away
It goes back to the words "Known" & "Cast". The Wizard's knowledge is stored in a book and he partially casts his spells in the morning. The Sorcerer, mechanically Knows X Spells of Y level including Z and they Cast the entire Spell at once. All four of these traits share the same two common words and it's easy to overlook the fact they can fully be referring to one thing and not the other rather than both.
