I'm sorry to tell you that, but the campaign has nothing to do with Angmar's Edain specifally. What is most important are the background facts from the books. And as the campaign also based on them, there are still many parts acurate, but not everything.
Angmar is based on the old
Angmar RPG , of which only some leftovers are available in German. That is, where are all the new Angmar heroes from, like Zaphragor, Mornamarth, Gulzar, Durmarth and so on.
Carthean is included in Arnor, as the name existed for a hero, who was quite similar and that was better than inventing a new one. Also, Men are know for reusing names quite often.
Arnor is based on the time of it's last battle against Angmar +-20 years, such that Araphant can be still alife and Aranarth can lead the people of Arnor into the woods. This timespan is a bit wider than for other factions, but all 3 of them where alife at the same time, such that there aren't any big contradictions.