From what I can tell, these boats will never spawn because they have no fishing rate modifier attached to them, which other fishing boats do have. As a result, they'll never spawn.

@EvametryE -- For some reason this boat won't spawn for my Anchovy Fishing Harbor. I thought there was something wrong with how I placed the harbor or drew the shipping path. I waited 4 game months and no boats spawned. I subscribed to a different Anchovy Ship on the workshop and poof...instantly multiple ships of that type spawned. I continued to wait for another game month and this boat never spawned. I just wanted you to know.

Thanks so much for making these SH compatible!