We have a tooltip that shows the time to finish constructing a building. It makes sense that we should also have one showing the time to finish repairing a building or unit. See the screenshot below.
The code is basically copied from D522 (and D572). So if further changes are made to that one then the same changes should be made here.
An extra thing in the repair code is repairTimeRatio, which accounts for buildings taking longer to repair than they took to construct.
I think this tooltip would be a useful addition, but let me know what you think.