Well I've struck out in nearly all the direct versions on the village Sedlice, so I looked closer at the transcript and villages, and like Mary Levesque had noticed, nearly every Bohemian village is not spelled right, either in Czech or German. I took the ones that I could find though, Neusattel and Mlaka and found both to be common near Trebon. I did attempt to find some of these names listed on the transcript, hoping another researcher is in the same area, but I didn't come up with much.
When I searched in these archives, I did find strong evidence of the surname Simic (Simek) in the archives of both Neusattel (Novosedly) and Mlaka. So close, as to think I had found them at first, as I found 2 close births to the children I was looking for. I am going to concentrate my search for now in the Trebon area in those parishes in and around those villages at first, then gradually move away. To move the search quickly, I am simply looking for the birth of the last Czech born child Josephine (Josefa), who was born about a year before they left, as the name is less common than Franz or Marie. If I can match child & parents, then I can expand backwards the search.
Might be just a coincidence that I found the surname near where others on the ship are from, but it's the closest I've come yet to finding a clue as to where they came from so I'm going with the hunch for now. Thanks again for all your great help and ideas!