More Words, Deeper Hole

My understanding about Rideau Hall is that there are dozens of buildings on the grounds and the plan hasn't even got to most of those. ("Six greenhouses"; if one of those is an Edwardian wrought-iron greenhouse, as I sort of vaguely recall, it's probably a restoration challenge all by itself.)

Plus the geothermal climate system for Government House is only about half installed -- in the sense of the first phase of the project is done but it's planned to be much larger if the first phase works -- plus whatever else still needs to be done for the interior, which almost has to include electrical as you note. ("tear out the 1913 ornate plaster ceiling? The 1890s carved baseboards?" etc. Figuring out where to run wires is not going to be easy.)

I shouldn't say "finished" about Rideau Hall, really; it's such a vast accreted pile that it probably can't ever be finished in the sense of "no outstanding maintenance". "Much more caught up than presently" might be the better way to put it.