I should add that the previous bug was with without "UseCIEColor" pdfwrite could not access/create device independent colours, hence was emitting a PDF with device dependent colours despite the "UseDeviceIndependentColor" setting.
The reason UseCIEColor has to be set explicitly, and can't be done as part of the "/printer" PDFSETTINGS is that the PDFSETTINGS is a parameter (or set of parameters) for the pdfwrite device, whilst UseCIEColor is an interpreter parameter.
I should add that the previous bug was with without "UseCIEColor" pdfwrite could not access/create device independent colours, hence was emitting a PDF with device dependent colours despite the "UseDeviceIndep endentColor" setting.
The reason UseCIEColor has to be set explicitly, and can't be done as part of the "/printer" PDFSETTINGS is that the PDFSETTINGS is a parameter (or set of parameters) for the pdfwrite device, whilst UseCIEColor is an interpreter parameter.