When you add anything in a sequel there are bound to be some inconsistencies (minor in this case, IMO).
The healers in Aleroth did not assume the well was the source. Starting a new game Joram mentions that the healers lost contact with the source (the shrine still being accessible, though inactive), and Goemoe makes a clear distinction between the source and the healing shrine.
It is not unreasonable that the dukedom of Ferol simply didn't have contact with dragon knights recently enough for them to be randomly brought up. The Orobas Fjords were also not mentioned in DD, but obviously the DD gameworld was not the entire planet, and at least some of the NPCs in the game would reasonably be expected to be familiar with other regions, especially ones relatively close like the fjords.
I would guess the dragon riders' mounts are more likely a sub-species of dragons or an unrelated species named for their appearance ('low flying lizard riders' doesn't sound nearly as impressive as 'dragon riders').
There was originally going to be a swamp in D2:ED (
screenshot 588KB) as well as an area containing elves and dwarves (possibly even the same map as the swamp), but they got cut during development.
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