From what I have seen in baptism/marriage/death entries Jos. is a common abbreviation of Joseph. John (Johann, in Latin Joannes/Ioannes) would have been abbreviated as Joan., Joa. or Joh. See e.g. that entry, first line, last column:
> coop. Joa. Ant. Mogetini p. t.
meaning interim chaplain John Anthony [Joannes Antonius] Mogetini.