You definitely want the sharp downward bend to match the profile of the skin. If the longeron angle wants to twist out at the bend, you must persuade it back so that when you lay the skin on the longeron it lays flat. It can be hard to get a crisp downward bend, but don't sweat it. There is some room for transitioning the bend. The twist in the longeron happens much farther down by the firewall. At the firewall there is a little bit of leeway between where the skin goes from flat sided to curved to follow the firewall. It is easy to tweak the twist at that end later when the firewall is attached.
