Game Guru does not operate in cells. It is very different from creation kit in all regards.
The feature you describe can however be implemented rather easily with the teleport commands.
Everything else you noted, except for the enemy AI where another update is indeed needed, has been done and some instances of it can be seen in the W.i.P and Showcase board. It is not a direct function of the software itself, however, it rarely is. The only software I know off that has all these features out of the box is the famed RPGMaker series. However, this tool is 2Dimensional and most content is heavily Anime themed.
Quote: "to actually make a game worth playing."
Please define that? Do you find all FPSCreator releases too amateurish to even bother? If so, I don't think you will much like what you find with GG.
This is a decent fps action game
made in fpscreator by Bugsy.
This is a fantasy adventure
I developed pretty far until I swapped to GG.
I'm a little bewildered by your grand dismissal of all our work because indie games in general didn't seem all too much better than this back then, unless there was a small studio involved. So, if you wish, please name a few indies you find enjoyable.
Anyway, just check out what games are being made on here and what you can do yourself with the tool. Also note that everything you have suggested here has already been suggested plenty of times. This community is not cut off from the rest of gaming
Lee is currently implementing DX11 so there will no major updates like you suggested any time soon.