ACTBUS, although centred around ACTION buses, has always covered all forms of (public) transport. Naturally, many bus enthusiasts will also have some interest in other forms of transport to various degrees. As ACTION became part of TC, it makes sense that light rail will become another prominent feature of this site. The admin/s have already incorporated categories for the trams in the gallery, fleetwiki, and forum quite nicely.
I personally think ACT Bus is a nicer (or equally nice) name than Transport CBR or ACT Transit or Transporty McTransportface or whatever else people can come up with. It's 14 trams up against 420 buses and >14 non-trams/buses. I doubt a name change and don't see a need for it.