Need Help Tracing Johannes Hermundsen

For anyone who may remember my search for Betsy Johnson (b. 28 Feb 1850), we've had a DNA breakthrough! We have a DNA match whose common ancestor should be only 3 or 4 generations back for my mother. This match has not provided specific lineage information to me, but he told me enough that I was able to find his well-traced line online. His ancestry is half Norwegian and half Danish. Since we have no known Danish ancestry, his Norwegian ancestry could get us past the brick wall for Betsy Johnson . . . finally! Of particular interest to me is Johannes Hermundsen because he is a good age to have fathered a child in 1850 and Betsy may have gotten the Johnson surname from him. Here is what I know about him: Johannes Hermundsen, christened 6 Jan 1818 in Vikoren, Vik, Sogn og Fjordane. Johannes's parents are Hermund Johannesen (b. abt 1776 in Gjethus, Vik, S-Fjrd)) and Marthe/Maritha Maria Siursdotter (b. abt 1780, also in Gjethus). They were married 2 Jan 1815 in Vik, S-Fjord. (This information comes from a family tree at FamilySearch.org.) Besides Johannes, known children are Magnilla (b. 1814 and the link to the DNA match), Martha (b. 1816) and Sjur (b. 1821). I found a record of Hermund Johansøn, Marita Siurs Datter and Magnilla Hermunds Datter in "Church book from Vik parish 1787-1820 (1417P). I have found lots of records at FamilySearch for Johannes Hermundsen, but I'm having a difficult time confirming if any are the right Johannes Hermundsen. If anyone can tell me more about this Johannes Hermundsen, I would be most grateful. Hopefully this will be a quick search for someone who knows his/her way around the archives . . . unlike me! Thank you! Nancy