Shadow Unit and Tech Icons

Is there any way to move the shadow/greyed out Icons from units or techs that are not yet available in future ages to different buildings? For example, move a knight shadow icon (available in castle age) from stable to castle for instance. Is this currently hard coded to their respective tech tree buildings?

You need to edit futuravailableunits.json within game directory for changing the location of shadow units and techs. Placing it under mod directory doesn’t work (due to a bug that the devs say they are tracking since 1 year)