Something to be "well known" and to be "largely forgotten" is not a controversy.

First of all, Sammael observation happen a way before Rand arrives to Arad Doman. During that time, Graendal easily Compelled large half of all nobels in Arad Doman. Which is pretty much what Sammael predicted - "every Domani who visited here left believing that this land had been handed down in her family since the Breaking".

Second, the nature of "well known" and "largely forgotten" are not that incompatible. The place may be very well known, as in someone says the name and you immideately recognize the name and point it. And the same name can be largely forgotten, as in someone is asked to say the hideout of Forsaken and the "well known" place does not come up in the list at all.