Yes, the automation will come eventually.
The easiest way is to create the desired contrast color for each icon with an image editor and then save it.
I have white icons for all non-active workspaces and black for the respective active workspace.
You make the assignment in the theme settings. I have a separate theme for each workspace.
In the settings, select one workspace theme at a time and set your own icon with the contrasting color there. Just try again.
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