What has happened is the stress of taking them in and out - the radical changes in environment. Once hardening off begins, they need to stay in that environment. Otherwise they aren't being hardened off. That means you shouldn't start the process unless the weather forecast allows it to continue until they can go into the garden.

Less experienced gardeners who try to rush planting out will hotly debate this - see recent discussions - but the validity of it is well established.

In your case nights of 40-50's are no problem for them outside. The severe storm? Perhaps but rather than bring them end you just move them to a more sheltered environment for the duration of the storm. Back inside and under lights is too radical a change.

Clearly there are exceptions, depending on the crop. A sudden snow fall or hard freeze for example. In which case bring them in but try to duplicate the outside environment as much as possible - cool basement with no lights, for example rather than the living room with lights.

What many fail to understand about the process of hardening off is that full bright sun tolerance is not the primary goal. Adjusting them to air temp and avoiding high wind exposure is. Dappled sun, what many call part shade, as long as they are protected from harsh winds and air temps below 40's is great hardening off conditions for most vegetable plants.

If you will move most of your tomato plants to such an environment they will recover assuming they are not rootbound in their containers. You may lose some of the worst leaves but the new growth will be fine.

Hope this helps.

Dave