I've made it to the end of Landscape Cities and caves... At the start of the FCOM section, it says that there is no turning back, so I assume if you messed up the FCOM part you must start all over from the very beginning. After running boss, rebuilding patch and starting the game, I see the awesome "WTF" missing mesh signs and CTD when trying to leave the sewer from a new save. I believe, but no way to prove it, that I messed up on FCOM part.