The build limit on domes doesn't apply to construction sites

[ChoGGi_2]

Console are maxed at 20 domes with:
const.DomeCap = Platform.desktop and max_int or 20

This function is what checks if you're at the limit:

function AreDomesCapped()
    return #(UICity.labels.Dome or "") >= const.DomeCap
end

but dome construction sites are stored in
UICity.labels.ConstructionSiteWithHeightSurfaces
UICity.labels.DomeBasic_Construction (depending on the class)

So you can plunk down as many sites as you want, and just turn them off till you want to build.

Edit: It seems the geodome (wonder) doesn't check the limit, so you can build that after you reach the limit as well.