Please use the "Norway" tag for discussion of Norwegian profiles. It will attract members with knowledge about Norway.
I don't know anything about this bygdebok in particular, but at first sight it looks solid. I can easily see that parish records and probates have been used.
The birth year 1677 of Trygg Andersen's, certainly derived from his reported age at burial, looks suspect. I'd estimate it to about 1690.
Also, please add the category for Frogn parish when you add or update profiles from this parish. It will help other researchers in the same area to find the profiles.