I play a 1680 x 1050 screen, Gigantic Map, all options set to 'Abundant'. I therefore spend most of my time on the overview zoom level, only zooming in when its mega busy around the area of interest. Gigantic Maps get busy, and with DA they became appreciably busier.
Bare in mind my comments refer to the zoomed out map - its obviously not an issue when zoomed in.
I get around seven or eight miners beavering away on a dozen or so Asteroid Belts that can be spread around a third to half the map. The initial build is fine, you get the Race primary colour as a build indicator for the mining station. Then it gets a little confusing. If there is a line of 3 or 4 mining stations, its easy to miss the fact that a mining build has completed as the ship is the same colour as the completed mining station. The icon is offset whilst building. and then overlaid on the mining station to indicate a finished build. However on the zoomed out map its not very clear and you can live in blissfull ignorance that a build is complete - it gets lost in the other activities you are engaged in (significantly more to sort out than in Dread Lords), and semi immersed in the other symbols.
That becomes more so as the build time increases with the additional Intermediate and advanced builds - cant track manually, and you rely on a game indicator to jog you.
If the Miner were to change to a unique colour on build completion (reverting to default when you move it), that would stand out from the rest of the UI. The possible difficulty of too many 'Unique Colours' in the UI is acknowledged, and in that event a symbol change to a symbol - say an octangon, pentagon, whatever - with a suitable color fill would solve the problem. This could be backed up by a "mining completed at" notice on turn end (the latter being 'clickable' to take you there would be the icing on the cake).
Not the end of the world of course, but it would remove a micro-management issue, and save the user squinting at the zoomed out screen in detail to check what the miner state is - on a gigantic map that can be a lot of squinting

Regards
Zy