I found the index for the years 1851 and 1857, but nothing in the "J" listing that could be Jasa. Since the ship's record listed Moravia, I think it is likely they were from there. You see it where Moravia is crossed out and Bohemia written in, for whatever reason, but I've never seen Bohemia crossed out (when it was correct) and Moravia / Mahren written in.
The index that I found contains entries for a handful of other villages, too, so if they were from around Neustadt, then you'd expect to see the name on the record. The link for the 1857 index:http://actapublica.eu/matriky/brno/prohlizec/6860/?strana=12
You have made a start. Someday you will find the records.