In order for you to cross, you'll need to do the midair jump when you are level with the first square of spikes.
And the enemies will need to be on the ground when you do the midair jump, because you need them to jump over you.
Juni falls faster than they do, so if they jump when you start your leap across, there's no way you'll be able to do a midair jump after they land and still live.
Unless they were already in the air before you started your leap.