Hi Spike,
Although Siril accepts RAW files and can develop them, I only use Siril for stacking and background/ gradient removal with TIFF files as input.
I use Photolab for RAW conversion and output to TIFF, only with minimal corrections in Photolab. So no Clearview, no Smart Lightning, et cetera.
I apply the preset ‘no corrections’ and then a subset of the optical corrections and Deep Prime, sometimes a curves adjustment for the offset of the blackpoint as first correction for the light pollution.
I turn off the Lens sharpness as this will introduce a strong halo effect around the stars.
I also turn off the Vignetting control as this can introduce a strange circular banding effect:
see Vignetting filter causing banding - #24 by LexB
But without the correction for Vignetting with Photolab you should do this in another way. Maybe by taking ‘flats’ and use these with Siril.
Lex