Such a trip to the Enchanted Forest, or what is left of it, certainly has impact on a person. Emma might have started to believe, that what Henry told is true, but think coming to the Enchanted Forest, seeing some magic there happen, experience it as reality is something now making it all more real for Emma. And it was some emotional roller coaster there for her. So of course she is changed.
Will she be able to trust people again? Yes, she already does, let down her guard somewhat, let people closer. She let Henry through her high walls, Mary Margaret as a friend before the curse was broken. Not to forget Graham, although it was more a delicate first attempt to open up again for a love interest, but she did, despite that it ended already in a second so tragically. Doubt she could have defeated Cora for the moment the way she did without all that happening before.
Heros are often send on a quest to not actually safe the world or whoever, but to find themselves.
Don’t think though that Emma is all there yet, that her quest is over, just a part of it. Despite that I said, that she already has begun to trust people again before the curse broke and her trip with her mother to the Post-Apocalpytic Enchanted Forest, Emma still has issues. Her walls might crumble, have become more transparent, but they are not gone. Some things no one overcomes overnight.
edit: of course there are more challenges in the future for Emma to deal with, but think trust issues are still there as well, She sure now has to deal with exploring and handling her power, what does it mean for her and for her family, that Rumple seems to have some bigger thing, plan going on, Cora and Hook coming to Storybrooke, what to make of Regina (wll she ever learn, that Regina did kill Graham for example, how will she react to that?), Henry’s future, sharing or not sharing parental rights with Regina, she herself as mother and daughter, geting to know her father, just to name what immediately comes to my mind.
(and for the sake of more seasons I hope Emma and other characters have to go through some more up and downs in their lives; there is a reason why it is called happy ending, end of story that would be otherwise 😉 )
¯\_(?????? ?)_/¯