Several quests require you to access the black market at Delver's Row. I learned the location of Delver's Row from a bartender. She told me the directions to get to it in the narrows and that it was behind a curtain near a merchant's stall. However, to access Delver's Row, I had to pass a rather steep perception + Streetwise skill check with only the Watcher's skills counting. Once I used svef to get my perception high enough, I was able to discover the hidden entrance that I already knew about. So I'm not 100% sure, but it feels like that skill check is only supposed to be there if you haven't already learned where Delver's Row is. However, so far as I can tell, the only way to get into Delver's Row is to pass that skill check, which requires a specific stat build for the Watcher.
Am I right that this is a bug and the game should recognize that I already know how that Delver's Row is behind the curtain?