2012-05-01: Support was added for Waymarked Trails. (Other news...)
Does “of on” make any sense?
Yes, it does. You are member of a group (%1) on a site (%2).
Groups is a plural word, so I would expect the verb used to be 'are' rather than 'is'. I would also expect to see a word between 'of' and 'on'. So it doesn't appear to make sense.
It's just contracted version of "Groups, that John Smith is member of (on $2)". I admit it quite hard to parse.
Meaning documented.
