as I can see through Scribus one cant push through transparencies in CMYK, thus not doable completely like that, as pointed bellow AD also has issue … need to check the KRITA option to save it as TIFF cmyk but probably this also has issue with transparencies too?
~
really not sure if AffinityD pipeline can be workaround, but its corporate software, thus Ghostscript should be only way out of this for now …
~ https://forum.affinity.serif.com/index.php?/topic/86583-how-to-change-transparency-from-rgb-to-cmyk/
