My notes from the marriage record at the church state that Tollef Anundson and Randi Tarjeisdatter were married 7/15/1853 by Rev. Adolph C. Preus at the home of Svend Anundson Sinnes, who, as you probably already know, is the husband of Dagne Tarjeisdatter, sister to Randi. Svend and Dagne lived in Pleasant Springs township, so technically they were married in Pleasant Springs township, not Christiana.
The only church in Christiana township was East Koshkonong; West Koshkonong church is located in Pleasant Springs township; Western Koshkonong (established in the 1890's) is located in Cottage Grove township, although it is just across the road from West Kosh.
The East and West churches, as well as Liberty Prairie church in Deerfield township, were all served by the same pastor, and the church records were all kept together. I imagine that is why it states they were married in Christiana township, as the records were probably kept at East Koshonong at that time. I checked a couple of the early marriages listed on familysearch.org that state the marriage took place in Christiana, when in fact the marriage took place at the West Koshkonong church...so I know it was Pleasant Springs township. Hope that made sense.
As to when your Rannvei Guttormsdatter died and where, I cannot answer that. I did not find her in the cemetery inscriptions that I have...assume if she died in the 1860's the stone most likely would be gone by now. The records for the churches were later stored at the West Koshkonong church and the burial records for the years +/- Oct 1853 to Oct 1893 were lost in a fire; the marriage, baptism, & confirmation records were all saved.
That "Christina" township listed in the familysearch.org files was just a typo....transcribers make errors like everyone else.
FYI, I am very familiar with T. G. Mandt...and yes, Randi, Dagne & Jorund are sisters.....oh...don't get hung up on the spelling variations....you probably spell them different than I do. :-)
Hope this helps.