Immigration mystery

I mentioned above my still unsuccessful efforts at finding the immigration records of my great-grandfather Per Gustaf "August" Anderson. It is really mysterious. I know that he came from Ulrika, a village in Östergötland, Sweden, when he was about ten (and he was born in 1859, so he would have come in 1869-70). I know he was brought by his grandparents, Petter Magus Andersson and Sara Catharina Persdotter. I know his mother, Sara Maja Persdotter, stayed behind with her husband and other children (August's half-siblings), and then came to America a couple of decades later after her husband died.

In the "emigration" lists from Ulrika parish I find this:

As far as I can understand this, the "Peter August Andersson" listed fifth in 1870 is my ancestor. This unfortunately doesn't give an age, but indicates he came from "Sten[kullen]," which is the farm where he lived. Also unfortunately, the "clerical survey" (like a census) for this period doesn't seem to exist, so I can't cross check with the page number of the clerical survey listed here. Then my assumption is that the last name here is his grandfather, Peter Magnus Andersson. Why he would be listed separately from the young grandson is a mystery to me. But this indicates he left with a party of two men and two women. The men would be himself and probably his son Franz Otto, who also came to America in 1870; the women presumably his wife Sara Catharina, and then I don't know who the other would be.

But then I found the following ship's passenger list record:

This is a ship's passenger list for the Albion, leaving from Gothenburg in April 1870. In entry 2370 we see "Gustaf Anderson," age 10, coming from Ulrika, which one would presume would be my great-grandfather. He is traveling with two older women, Sara Catarina Anderson and Sara Maja Anderson, the names of his grandmother and mother, all from Ulrika. But the ages of these women don't match the ages his grandmother and mother should be (they are about a decade too young). Furthermore, if this is the right family, where is Petter Magnus Andersson? And why is Sara Maja here, when she stayed in Sweden? And why is Sara Catarina listed as "Andersson" when one would expect the Swedish records to list her by her own patronymic, Persdotter? Yet the emigration records for Ulrika show no other persons in April 1870 with names anything like this.

They appear to be bound for Jamestown; far as I can tell, there are three Jamestowns in the US, in Virginia, New York and North Dakota, and none of these states are associated with this family as far as I know. The family, my great-aunt said, came first to Pennsylvania, but then fairly soon to Nebraska.

One can see why this is mysterious . . .