Hey if it flies, it flies. I'm also second guessing myself here.

The magnets on the bell are not very powerful. The real energy comes from the electromagnets in the middle. Those change polarity based on the direction of the electric current.

If the next position on the bell is a north pole (+) and the electromagnet is causing the nearest motor's pole to also be north pole, then the two magnets will repel each other and slow the motor down. If not, they will attract and speed the motor up.

So yeah, I'm like.. 95% sure the polarization is important, but that if you get one wrong the rest should probably overpower it and allow the quad to still fly. Just not as well as it could. It might or might not even be noticeable.

If it flies, you're probably fine. If you try taking them back out after JB welding them on, you're probably more likely to break something than slightly improve it.

I'd say fly it, have fun, and you'll probably break one and end up replacing all of them in 6 months anyway.