Hey keksonja o/
I just noticed there is a bug yeah when you turn off Create Background, in fact the rayswitch should always use the fg port to provide the lighting and it's currently not the case ( something that I destroyed when I improved the template). I will correct this, it's just a line of code.
The Background texture now stay visible in the viewport. It's more user friendly this way

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The excessive sun brigthness is certainly caused by the physical sun shader option, I need to average it with the classic sun (at leas find about the same intensity output).
I know for the rotation thing, it's an old thing I need to correct !
I will release an improved template really soon (1 hour max) that should correct all this (except maybe the feedback rotation).
See you soon and thank you very much for testing !

Thomas
Edit : Oh and for the sun brightness thing, since it's rendered in linear workflow you should compensate your input colors :
a 0.5 grey should turn into a 0.5*(1/2.2) = 0.22725 one (that may explain why you find the sun really bright)
And for the rotation thing, in fact the script is crashing when you desactivate the feedback creation :| It should be fixed in the new template.