I agree with Lena, the spelling doesn't matter. It cannot have mattered much to the people themselves - I don't think most of them could write; they had their marks to sign with.
As for Mårtensson, yes, I think you are settling for a good policy, anchoring it in the political changes in New Sweden (and where the person was born).
There are a number of New Sweden women that I'm "meeting" in the error report, I think I'll collect them into a list soon and come back with them.