Okay, I figure since you may still be asking for suggestions I'd give my input. This is a list of things I'd like to see done for galaxy forge and what I feel would make it a LOT better.
1.) Faction naming. When you set the in-game name for a faction, that name should appear as selected in the game instead of the default AI faction names (such as Arn Consortium or Nithiem Rebels or whatever) and instead of whatever the player chooses as a name. This is a basic mechanic in galaxy forge that simply doesn't function and needs fixed.
2.) Fix the map editor so players really are restricted to a certain race. It seems you have this option available, yet it doesn't work. In the event of AI playing, allow us to determine the attitude and difficulty of that AI. For instance, a player joins a game and sees that one of the AI is an advent set as a researcher on vicious. Locking certain player slots to certain factions would also be good. For instace, player 1 would be TEC starting out on the west side of a map, player 2 would be Vasari starting out on the east side of the map. Also, your Galaxy Forge has a habit of ignoring what map makers set as the starting gold, metal, crystal of each player. Fixing that would be an improvement.
3.) Fix militias and pirates so one doesn't need to open up the notepad and change the Planet Owner section just to ensure their pirates/ militias show up. For those of us who know some coding, its not too much of an inconvenience, but for a system that claims to be user friendly, having multiple parts of your program require its user to bypass using it in favor of altering that code in a notepad or textpad seems counterproductive and highly inconvenient for those who may have no experience in coding otherwise.
4.) Allow us to change the names of the militias. Just as we may want to alter the names of all the players currently in-game, we may also want to change the name of the militias involved. This would be highly useful for those of us looking to make "campaign-like" maps.
5.) Update the Galaxy Forge so players can use the recent ships, bonuses, artifacts, starbases, etc. introduced in Entrenchment and Diplomacy. A mod was published by a player that allowed people to do this with galaxy forge so there's no reason you, as the official source, shouldn't be able to.
6.) Add the ability for us as map builders to alter the level of starting capital ships and decide what upgrades starbases will start with. This would be nifty, as stated, for campaign purposes.
7.) Allow us to determine at what research level players will start out with! It might be cool starting players out at max research or at varrying levels of research depending.
8.) Allow us to determine the starting diplomacy of the players as well. For instance, are certain faction currently at war? Are certain ones at peace? Are they allies? Are they at peace happily or is the peace undertoned with disfavor and on the verge of breaking? It'd be great altering not only who is allied or at war with who but what level of favor they are as well.
9.) Being able to zoom out further would be VERY helpful. You have no idea how frustrating it can be, especially when you have big maps with many systems involved, to have to constantly use the scroll bar.
10.) An undo function as stated is a must.
11.) Deleted objects should not drag down the whole game and should be deleted. Its very awkward clicking on the spot you deleted an object to find it still apparently there.
12.) Improving how the editor runs would be nice. I'm running a fairly good computer with an i7 processors and yet the Forge can barely handle it and my computer heats up greatly when multiple objects are being used in the editor. Finding some way to reduce the amount of memory it takes to run it would be great.
13.) Don't know if you can go THIS far, but giving us the ability to determine exactly where objects are placed in the gravity wells would be great. Can understand if that's too complex though.
That's all I can think of for now, but I think that covers the important bits. I know its been beat to death that you cannot add a Z axis so I won't even bother asking that. Hope this list helps you determine some ares to focus on. I will update it if I think of anything else.