You may need to use cyan filters for Ilfochrome printing due to the fact that it is daylight balanced. You use M+Y filters for negative printing because it is tungsten balance. (this is an oversimplification)

Do not use all 3 filters for reducing light intensity because it can introduce a color bias. Use a true neutral density filter for that purpose, or stop down the lens and reduce the exposure time.

In rare instances lately (2+years or so) there have been reports of Fuji CA paper requiring cyan filtration. My investigations so far say that there were either problems with the paper, or the process. CAII paper, introduced in 2006 requires a new developer and development time.

PE