Due to the differences in pressure between the .380 & the .9mm I would not try the swap. Yes,, they might fit. Yes, it might allow easier racking of the slide. BUT,, it will also cause harder impact forces upon the frame when fired. That could damage the gun.
Springs are built to a certain tension for a reason. To allow the gun to properly operate AND function correctly.
I would instead, learn different methods of slide racking,,,or even get one of the inexpensive tools that is a slide racker assist.
I've taught classes to MANY older ladies who found that slide racking is a problem. Yet,, some were able to learn a different method, and became capable of operating their semi-auto's.