She really is a Mary-Sue, and I'll explain one reason why.
You see how Steven practically became the Jesus of the show? Always the "voice of reason", the pacifist, the "leader", and the one who spouts preachy on-the-nose garbage at the end of each Townie episode? Well, whenever Connie gets involved, like in the latest bomb and in the Initial D rip-off episode, Steven either becomes incompetent or preachy about how everything is his fault or downright retarded. Connie will be the one who does Steven's consistent bullshit, giving out the message and acting like the sane one, and the writers are basically painting her as someone who does no wrong, even though she ran away after harming a kid and acting dramatic about it like her life is over.
Remember when Steven was insecure about his height and turned himself into a baby when Connie gave him the shirt? Remember how she was made more experienced with kids than Steven's father and the two mother-like parent figures who took care of him for over a decade? Remember how she's the one advising Steven better than Pearl? Remember how they made Peridot and Lapis out of character just to give Connie an excuse to act preachy and be the voice of reason yet again?
Remember how she mastered swordsmanship in an extremely short time off-screen and being more combat capable than Steven?
She's the show's unofficial poster child, she has virtually zero flaws and is somehow better than any other well-written characters, and she was fine as she was in Season 1-2 and it's horrendous they made her this "perfect" later on.
Goddamn, I basically gave up hope on anyone writing her better, she'll still be as bad in Season 5 as she was in 3 and 4.