The answer is, no there is no way back out of the Giant of Babil. Unless you have a save game from before, you are there until you get out. As for the best place to train.. unless I am mistaken there is only the one save spot, I would recommend just hanging around there until you feel ready to give the Four Fiends another shot.

Yeah, one thing I have learned, for games in general but RPGs specifically, is not to constantly save over the same game. That way if you need to go back, the option is available to you. Actually, for FF4, I have been using 2 memory cards so that I have 8 save slots available.

For where you are now, I would recommend using both Rosa and FuSoYa exclusively for healing your party. Don't worry about using up all your MP, as long as you stay just a few steps from the save spot you can always rest up (unless you've been careless, you should have at least enough cabins to get you up a few levels.) Beyond that, most of the things in the Giant of Babil are weak against lightning, if I remember right.. so have Rydia use Lit2 (and, if you are SURE Rosa has the healing covered, have FuSoYa use Lit3).

Let me know if you have any luck with that.

Lol i remember I got stuck here and had to restart the game, I was rushing through it so I could show my little cousin the story and got there within 8 hours on like level 20-25 on the old SNES with no items, sadly I had to restart the whole game.

Thats the same part I got to on the game, and I gave up, I might go dig up my FF4 and start it again....

Gah, so much to do, so little time.

If you have to level up, find the warphole you came out of or, battle lots till you build up that way.........i dont see why you would have trouble here.....4 fiends are not easy but they are not impossible......you should have your nuke by now as well so........
good luck anyway, and if you still cant find your way out, keep looking there is one way!