There were a couple of difficulty spikes in the original release of Ego Draconis, which made it less forgiving in some places if you went into areas above your character level.
There was also a level dependence in combat in the original release, reduced in DKS, which made opponents more than a few levels below your character not a threat even in groups, and opponents more than a few levels higher pretty much impossible.
Level 30 is a little low for the Hall of Echoes. Average end level is in the low to mid thirties, with 36 about the highest you can get without taking advantage of a couple places where opponents can respawn.
It is unfortunate that you are at a dead end... Can you backup your save to a flash drive and try it in your friend's Xbox? It wouldn't quite be the same, but you could watch the end of a Let's Play on youtube to see the ending.
In any case, the add-on Flames of Vengeance is only available as part of DKS on the Xbox. Missing the last 10 minutes of D2:ED isn't really a big deal if you are going to get DKS anyway, and if you don't think it is worth getting DKS to conclude the story of the Dragon Knight, then stopping slightly earlier than you were planning to shouldn't matter either.
FoV became too large for DLC, as was originally intended, and Larian could find any publishers for a retail release except in Germany.
