Unable to add a category page in this message meaningfully. Since this page uses page title without brackets to create link, adding the title of the category, categorizes the special page [[Special:ListGrants]] instead of linking. If we add ':' as prefix of category hoping link will be created as "[[:Category", it also fails since colon indents the text.
Hi, thanks for reporting this. I'm not sure I understand the problem. :(
This should not be a link to a category page but to a help page called Help:Group_rights (in English). This link is used on Special:ListGroupRights and should not go to വർഗ്ഗം:വിക്കിപീഡിയ_ഉപയോക്തൃസംഘങ്ങൾ / Special:ListGrants (which you mention above).
I understand that. Currently Malayalam Wikipedia has no such help page. But we have project pages describing each user group. I tried to link the category containing all such project pages, which is not possible. I am trying to report that the message is too rigid, in case a wiki user need to link a category (as happened in ml.wikipedia).
This message also uses in Special:ListGrants through MediaWiki:Listgrants-summary.
You can use : in the message to link to a category
it looks only "wrong" with the indent when the message is parsed in the mediawiki namespace to show its content, but it should work as expected.