Resetting springs involves heating the springs to remove the 'spring' in the steel, then reshaping them to the new setting, followed by another heat treating to restore the 'spring' again.

There have been innumerable attempts at re-arreanging the spring stack, reversing one leaf etc. etc.
While this may affect the static ride height, it also alters the spring rate, often for the worse & also leaves the main spring leaf unsupported in some cases which means that the car is both unsafe & illegal.

If an unsupported, or inadequately supported main leaf breaks between the front anchor point & the axle the car can easily end up being 'rear steered' when that side moves backward, jamming the tyre against the wheel arch.
If this happens at speed, you're going to need a lot of toilet paper & possibly an ambulance.

The main leaf may not break only when going over a nasty bump either as it can develop a crack at the highest stress point. which slowly propogates & fails at any time without warning.

Resetting the rear leaf springs is really the only way to do it properly as the spring works should also stiffen up the spring rate while their at it to compensate for reduced suspension travel.