I've not played for ages, but quite a while back I remember modifying 2 of the original secret objectives that came with the game. The general consensus was that one was a bit too hard and one a bit too easy.

Time has passed and no errata ever appeared, so is the consensus now that these 2 cards (sorry cant remember which) are now ok?

Not heard discussion on SOs for a while - I think Regulator is generally acknowledged as being the hardest SO. I don't remember any mods though.