I agree that the Latin probably doesn't help with the identification of Margareta; I read it as something like admissa ad sacram. coenam. which is to say she had been admitted to partake of the Holy Supper. So either it does not refer to Margareta or the it has been added to the page long after the years written at the top.
Your advice that Ersson and Ersdotter should be entered as Eriksson and Eriksdotter makes perfect sense according to the Swedish practice to standardize names in genealogy. This is contrary to the WikiTree policies to use the spelling from the sources, which admittedly does not make all that much sense for Swedish profiles. The problem is that people including myself have been using "spelling as from sources" here for years and years and years.
Edit: I see that you went over the Latin again and came to roughly the same conclusion.
