It's pathetic to see Angelique so earnestly taken in by a witch (warlock) using witchcraft to put suspicion onto someone else, which she holds the patent on, I think. Then there's the convenient, eternal cause for people making mistakes when they clearly know better: over-confidence.
Gerard should not have walked in just then. He should have done something to let Ang know he was nowhere in the vicinity when she was looking into the fire. But then, he got away with it. Maybe a witch would know that you'd usually need equipment and audible incantations etc.. to do the spell, and he supposedly was too close to have done it all, in the foyer.
Yes Ang, Quentin gave the doll to Gerard, but Gerard owns it now, and since it's his, he's an obvious suspect. Angelique herself is much better at this suspicion-shifting than Judah, yet all this works on her.
More and more, I see 1840 as some sort of timeline unconnected to "present" 1970 or 1971. Sure, upon returning to 1971 B&J find history fixed, but what if 1995-summer '70-1840 was one big anomaly or temporal bubble for some reason, and they were returning to a 1971 in which none of that happened in the first place? Or it's still early in 1970? Then they could find the present safe and sound, without ever having really done anything in 1840 that affected the present, the "real" present.