A couple things ^_^
1) Especially since I totally left Iskessah hanging last time, I'm inclined to be lenient about the map. Even if Charm kept the original with her, she was the only one on the voyage who disappeared, and so the rest of you had the whole long trip back to Zeltiva to think it over. If you feel like it's something Iskessah would have eventually thought of -- even if she just made a copy of a copy -- I'll let you have it. At the very least, she's seen it before and taken a good hard look at it.
2) The library in Abura isn't written up yet (getting there!), but they've got multiple copies of the Circumnavigation. You wouldn't necessarily need to think of it before you left.