So I'm getting to the point in my first real campaign where I have dozens of colonies over several systems, and scrolling through the economy window to find one specific colony is kind of tiring

Much like how the Fleet Organization Window organizes fleets underneath their respective naval commands, I think it would be super useful for colonies to be organized the same way in the economics window, so each system with a colony that is part of a sector is shown underneath its sector command.  Systems with colonies that are not part of a sector would of course be on the same "level" as the sector commands.

To prevent getting in the way of the "by function" checkbox, this display could also be toggled on/off with a checkbox.  Checking both the "by function" and "show sector commands" boxes would sort colonies by function, within their respective sector commands.