GENDER and !!FUZZY!!
In the message group Wikimedia messages, I have got rid of the GENDER magic word in some messages, for example MediaWiki:Group-botadmin-member/cy. I am now getting the missing parameter warning and the messages have been automatically marked !!FUZZY!!. I thought that GENDER was optional?
I think the most common practice is to leave it as in the English source, with only one parameter for the "unspecified gender". Translate can't know if gender matters in that specific message in your language. The optional use of GENDER is the "second feature" discussed in Gender ({{GENDER:|...).