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You can tell the report "Changes in Solar Brightness Too Weak to Explain Global Warming" was not written by true scientists, because true solar scientists know that "brightness", the visible spectrum of energy, does not tell the whole energy story of the sun.

Nor does that conveniently left out fact reveal that every other spectrum of solar energy is received, and affects earth's atmosphere in some way.

One report in this forum today noted a recent NASA study indicating, based on Nile river system data, changes in the sun's ultraviolet output affecting warming/cooling cycles.

An earlier study has also demonstrated, in laboratory proofs, that increased ultraviolet radiation increases the formation of clouds. Water vapor held in clouds is a far greater contributor to warming than CO2. Studies of the past 30 years, worldwide, indicate fewer "sunny" days. More clouds, more cloud-held water vapor, more warming.

I don't know if they used the full spectrum or not. I do know that other satellite measurements of the sun's full output don't show a lot of change in the few decades they've been measuring. Clouds are complicated since they can warm or cool. Obviously daytime clouds cool and nighttime clouds warm. From there it's not simple, high clouds warm because they are cold (see any IR satellite picture). Low clouds may warm or cool but since their tops are warm they may cool more. Clouds in higher latitudes warm in winter (less sun reflection, more heat trapping in those longer nights)

Water vapor is a whole nother ballgame. Like clouds it requires a huge amount of detailed weather modeling to get the effects right. Water vapor does not need clouds to produce its greenhouse effect. WV traps more heat in the upper atmosphere than in the lower which again depends on weather (convection) to get it up there. When the UV hits it and it turns into clouds as you suggest that would probably produce a cooling effect since that would only happen during the daytime. But I am not sure and it certainly is not a simple problem.