Before the MK3-MKT games, yes, Outworld was once Edenia.

However, with Kitana's UMK3/MKT ending (if I'm not mistaken), it reveals that her parents were the rulers of a realm called Edenia, which was taken over by Shao Kahn and merged with Outworld. So basically, it's a retcon. However, this retcon is a good one, imo as it expands things, making them more interesting.

No Outworld was said to be cool before Onaga ruled it, but Edenia is a realm in itself as hinted in Kitana's UMK3/MKT ending and MKD.

Yeah, but before UMK3/MKT ending of Kitana, Outworld was once Edenia from what I understand now, this was even before Onaga ruled it, but Edenia is a realm itself now, no doubt.

We know NOTHING about what Outworld was like before Onaga's rule. I already cleared things up here.