The way to correct the Minicraft 757's wing problem is to cut the fuselage into 3 parts: nose, wing section and tail, then glue them back with the nose and tail at a slight angle to the wing section. Then the wings will sit level once everything's assembled.
The kit itself is very buildable with few fit problems, sink marks, ejector pin marks or any of the other usual modelling gotchas. It's just a pity that Minicraft got the shapes so wrong

Still, it looks like a 757, and a kid doing her[1] first model won't care about the shapes.
I've found that Minicraft's decals can be iffy. Sometimes they work fine, others they destroy themselves. My TWA MD-80's decals started shredding, and when I tried coating them with Microscale film the gold washed off like watercolours in the rain. I had to strip it and use an aftermarket sheet. Since I don't often buy kits for the box scheme I don't let it worry me.
Minicraft is famous for getting the wrong parts into their airliner kits. They're also famous for customer service, so if you do get the wrong parts in your box, drop them a line and they'll get you the right ones.
[1] Or his. I don't want to get sexist
