@l0lag0lag0b3 - I have not experienced any elevation in my WBC count when my Tacrolimus dosage has been reduced. And, over time my trough level goal has been reduced from what was my during my earlier post transplant years. I am approaching 16 years post liver and kidney transplant, and I think that my current recommended Tac trough goal is same as
yours.
To answer your question about possible raised WBC - My WBC level has remained consistent over the years, and has not been affected when my Tacrolimus dosage has been reduced. However, I want to add theat whenever my Tacrolimus dosage has been reduced, it has been at only with 0.5 mg daily reduction. And my labs are repeated within 2 weeks to be sure that my liver and kidney are not adversely affected!
BTW - My experience is that it is okay for the tacrolimus level out of the specified range because of our individual reactions and health conditions. My transplant team looks at pattern over time alongside my overall health and lab results.

I hope that you have success with lowering the Tacrolimus if that is what your kidney doctor recommends. Is your transplant team involved? How will any change in medication be monitored?