Thank you for your comment. I'll think about it, but maybe this video will help you to beat it on normal as it is now. Level 4-2 is at 1:22. Reply please if it helps
I will say that I agree with the sentiment that 4-2 is far too hard.
I think adding some grapple points to the map so you can get back easier, and move around generally easier would help a lot. But I think a bit more floor to run around on would help too.
One problem with it is that you can't shoot your weapons while in the air. they either aren't good vs the enemies while jumping around, or launch you far off the level. Then when you're off the level you can't get back on because grappling onto a ghost medusa is probably certain death.
This means you have to play it in a way that is counter intuitive to how the rest of the game has been training you to play.
On top of that its also really hard still, and swapping between homing rockets and electro ball is important, while also being fairly hard to do at the speed the level demands with ghosts flying at you constantly
And on top of that the map is very small and hard to navigate. there's only two jump pads and they're very important for getting high up.