I think you got it right, all your assumptions. A patronymic surname was a fact, and could not be changed. Henrik Olsen was a son of Ole, and Henrik Kristiansen was a son of Kristian. The farm name surname was an address, and that was a changeable fact.
The confirmation record 1816 says that she was baptized 3. Sunday of Advent 1799 in Modum church. I have not found it there. May be her father and her eldest brother Ole were dead in 1816, and the pastor had no baptism record in his books to check up, - and that he knew one brother of Mari, Christian Henriksen Vesetrud, born 1787. Maybe because of that the pastor made the mistake of naming her father like Henrik Christiansen. - Maybe. Christian Henriksen was a servant on Vesetrud in 1801 census, and he was a witness by Ole Larsen's baptism in 1828. Kolkinn, Vesetrud and Berggården are neighbouring farms. Map: http://kart.gulesider.no/m/nmQ7fhttp://kart.gulesider.no/m/nmQ7f Burud is also close by.