About [[MediaWiki:Nmembers/en]]
There is no functional difference whether the number is outside or inside the message. You might have seen some different version of the message, perhaps local override, or older version because LocalisationUpdate hasn't worked a while.
OK, this is getting weird. http://hi.wikipedia.org/w/index.php?title=%E0%A4%AE%E0%A5%80%E0%A4%A1%E0%A4%BF%E0%A4%AF%E0%A4%BE%E0%A4%B5%E0%A4%BF%E0%A4%95%E0%A4%BF:Nmembers&action=edit shows that the message is not present locally, and is the new (current) message. Still the numbers aren't showing up at http://hi.wikipedia.org/w/index.php?title=विशेष:WantedCategories&limit=50&offset=4700
The numbers do show up with uselang=en
Any idea why this is happening? Should I try setting the same value twice in the PLURAL (meaning give it the same parameter for singular and plural both)?
I'm as puzzled as you are. There should be absolutely no difference between using numbers inside or outside of plural. It must be something else, like I said before.
Filed Bug 38615 for this.
It might have something to do with $digitTransformTable being set to international numerals on hi-wp since setting uselang as hi on en-wp makes devanagari numerals show up.