Instance variables to Local variables w/o breaking the functional flow, can copilot help?

[TechnologyTiger]

Question

We have a huge monolithic Spring Java codebase which has a lot of class variables defined in the Java classes (Spring Beans)
Since these class variables are not threadsafe, we see a lot of concurrency issues in the applications and batch jobs, as there are complex functional flows built using these variables.

Question: Since above is a widespread problem in the code, where we have thousands of class files and over 250 thousand lines of code. Can AI/Github Copilot help convert Instance variables to Local variables without breaking the functional flows built using these variables in multiple functions? If yes, how should we approach this?
If anyone has attempted to fix similar kind of problem, please share your experience.