This post is recommendations that I think can help improve the benefits and usefulness of radar and the empire tree.

Radar placement. Since terrain affects radar coverage, show a ring indicating a radar building's projected coverage area, factoring in terrain and radar research, to help us in selecting a location for placement. This will particularly help new players who might not otherwise put much thought into the terrain's impact on radar coverage. I strongly recommend this for the Vision global ability as well, since I have on many occasions placed that global ability on an area that cannot see where I really want it to due to terrain.

Empire tree. In Sins the Empire tree had additional usefulness in concisely showing us the ships other players had in a particular sector. Fog of War in Ashes complicates that, which is perhaps one reason you don't do it. But with your recent change to the Empire tree (dots) coupled with radar, you might be able to make it work. The empire tree could show the full icon for enemy units revealed by vision, but also show the generic dots for enemies seen only by radar. For instance, radar distinguishes the tier of units, and distinguishes buildings from mobile units, and this is shown in the empire tree, but it cannot distinguish which units/buildings specifically, so for those we would only see generic appropriately-sized and shaped dots.