After Feb 1st Riksarkivet SVAR will be free of charge. Then you should be able to follow up on this birth record:
https://sok.riksarkivet.se/bildvisning/C0035049_00047 Piteå landsförsamlings kyrkoarkiv, Födelse- och dopböcker, SE/HLA/1010154/C I/2 (1714-1756), bildid: C0035049_00047
For Johan Ersson, born - no, baptized - 11 August 1727 the mother is just in the book as hustru Kierstin. The father is named Erik Frigifven - I think it must be a soldier's name, so he may well be a Johansson. Very odd as a name, means "released" so maybe he was a returning POW.