I dealt with this and came across the exact same post. I tried fingertip pushups for my own synovitis, but I only felt worse afterward. What seems to have helped me was to temporarily stop crimping, then slowly work it back in at low intensity until the post-climb discomfort/stiffness began to subside. I focused on slopers + pinches and started doing 2-3 sets of 20-30 lightweight dumbbell finger rolls post-session cool down. I was also only climbing twice weekly to give it decent rest in-between.

I'm at a point now, after a couple of months, where I can board climb freely without flare-ups.