"The painter paints a farmer in the picture."
Translation:Pictor agricolam in pictura pingit.
Does the macron over the a in picturā matter here? It seems like it'd differentiate between nominative and ablative...
I don't think in is ever used with the nominative, so I don't think it matters in this case.
But if you are using macrons it is probably best to be consistent and use them where they are needed.