What is the best way to adjust the CSI? I can raise either the PH to 7.8 or the TA from 80 to 90 and the CH from 280 to 350 to get the CSI to say balanced. My current results:

FC 16 (still shocking the pool, though the PH has been stable for the past 4 days despite the 12+jugs of chlorine)
PH 7.5
TA 80
CH 280
CYA 50 ( after almost 2 seasons and countless drainings/refills)
CSI -0.32 (potential to become corrosive to plaster)

Thank you!

High FC levels and give the PH a false reading. I wouldn't do any adjusting until the FC drops below 10. When it does, retest the PH. You may find yourself having to adjust the PH in addition to the TA.

Congrats on bringing the CYA into range.

Two points. First, you actually want CSI to be a little negative, PH tends to go up and heaters and SWG have higher CSI internally. Second, it really isn't worth trying to balance your CSI to any exact number. All of the numbers will vary over time, especially PH. Trying to micro manage your levels uses to many chemicals.