Infact Sanskrit was one of the early communities to adopt Narayam (before Tamil). Please see the below screenshots for Tamil, you similarly have "Input Method" dropdown at top of page near Username / Login link. Please hover over it, you would get a dropdown to choose the transliteration option. (Control-M) is the keyboard shortcut to turn it off / on.

Gerard / Santhosh / Junaid / Shiju,

Should we run site notices with these screenshots on these communities to increase awareness. Tamil wiki projects have a link to typing help on sitenotice and that page contains relevant help. I think it would be better if you ask bug filers to make sure they run sitenotices on wiki post enabling Narayam to spread awareness.