Maybe you are right about Dipper needing some friends his own age, but I don't think Pacifica is a good candidate for that either. Maybe I'm bias because I hate Pacifica and I love Dipper, and I wouldn't really mind them being friends too bad, I just don't want them to be a couple. However I think it would be even better if a new character was introduced as a friend for Dipper his own age, like another boy or something.

As for how he acts around the teenagers... yeah I see what you are saying but I always found that awkwardness funny, idk, maybe I just like awkward humour funny. I guess it's really down to preference of humour at that point, some people like awkward humour, some people don't. But I liked it. When Dipper is around just Wendy, like in Into the Bunker, I would say he's his normal self. I want more episodes like Into the Bunker. Where Wendy is helping out with the mysteries of the town. I also would like just more character development for Wendy in general.

You said that Wendy always ends up getting Dipper in trouble when they are both goofing around, and yes, that has happened on a few occasions, but I don't think it's like her intention or anything, they just both like being silly sometimes and Wendy is simply better at getting out of trouble for it, probably because she's older and has had more experience getting out of trouble. And it's never anything that bad either. If Wendy got Dipper into some kind of fatal life or death situation just so she could get away with something I'd see what you are saying more. But as it stands I don't think Wendy is a bad influence or anything. I think they both just have a silly immature "let's goof around" side to them, and Wendy's better at avoiding trouble.