I must say the author of the codex fluff story has managed the impossible: they managed not only the first canon appearance of a female custodes, but she also is a fan-favourite now.
Everybody drawing custodes ladies with elaborate long feminine hairstyles and crazy intense makeup is insane. Have you seen the current custodes heads? They have the most dyke looking fucked up buzzcuts on earth broken up by 6 separate cybernetic skull ports, and the ladies would be no different. The only ones who even know what eyeliner is are in the Emissaries Imperatus shield host and would only wear it as an obscure means of communicating rank or authority in niche diplomatic interactions.