I think you are ok on CSI. I prefer 0 to -0.3 myself anyway. Especially in our region where our water has much more tendency to scale than to etch. You have plenty of chlorine in the where so I think risk of etching is very low.
Don't worry too much about rain and minor fluctuations in cya, CH and TA. Tests within 10 or 20 of prior tests are fine. Always round up on CYA to the next 10. And if in doubt keep FC 1 or 2 ppm higher. More FC is always better than skirting too close to minimum. Especially with lots of swimming.
Good job working those numbers!
Don't worry too much about rain and minor fluctuations in cya, CH and TA. Tests within 10 or 20 of prior tests are fine. Always round up on CYA to the next 10. And if in doubt keep FC 1 or 2 ppm higher. More FC is always better than skirting too close to minimum. Especially with lots of swimming.
Good job working those numbers!