Week 8 of flower I lowered the CO2 to 1200ppm and ...

I would keep running your co2 at 1200 ppm until you have started the ripening stage. It looks like you still have 3+ weeks left just a guess. Hitting her with extra PK should bulk up those buds over the next couple of weeks. To maximize her ability to pull nutes through her roots I would keep your humidity at 50% to keep the proper LVPD( Leaf vapor pressure deficit) https://www.blackdogled.com/lst This has to do with plant transpiration. https://vpdcalculator.com/vpd-calculatorI would start checking the trichomes when 50% of the white pistils have dried and turned orange. Theres some debate over using higher ppms of co2 is beneficial during the late ripening stage most professional growers back off to atmospheric levels during the last to weeks before harvest so it's not wasted. If she's in an enclosed space I would try to maintain a lights on level at 400ppm During the last 2 weeks drop your humidity levels to 35-40%. Hope this helps👍

Light intensity in that case is mostly a matter of temperatures as CO2 is allowing you to grow with higher temps so if the light is too intense it can be too hot and too hot can lead to high temps. I would like to say that CO2 is not a nutrient ( I mean plants eats it but in an optional way as it is not an obligation to use it) so you don't need to decrease the a CO2 input , use it until the end if flowering to increase tour yield.