Given this hasn't meaningfully progressed in years and there's no immediate future where it will continue construction, is it worth removing the construction tags?

Yeah as of yesterday the line and platform has been switched over, so platform 2 is now operational and platform 1 is currently not.

Yes it's a bit confusing but the trains are operated by transport for Wales rail, this is a subsidiary of transport for Wales the Welsh government transport org who own the core valley lines from just west of Cardiff Queen Street all the way up. (And also to a bit West of ninian park).