This one was missing some battens, which I noted. I’d like to ask though about the horizontal gaps between the seperate boards, as seen in the second picture. There were many.
Is it an issue? I presume so as both wind driven rain and rain dripping down the board above it would end up in the gap. Can it be caulked? I found one internet source that says to caulk the edge on either side of the batten.
Paul-Marc, Those butt joints should be cut at a 45 degree angle with the top over lapping the bottom but in your example it’s probably unlikely it will be corrected due to the amount of work involved, I should also add that when we do siding we install a small piece of roofing felt paper under these joints for added protection.
At this point I think your correct in recommending repair or replacement but not caulking as this would not be a permanent fix, although probably the most logical. The light should also be on a block of wood that is thicker than the siding, nailed to the sheathing and then the siding would be cut around it and flashed, again the most logical fix is to caulk it with clear silicone.