It would seem that in the quest.xml that the line requiring you to craft the farmer station says just 'farmer' when it should read 'farmerBlock'
<quest id="Q_Farm_E4" group_name="Food for Everyone" name="Survivor's Farm 4/6" subtitle="Farmer Station" description="While we waiting for survivors, we can prepare a Farmer station.\nCollect materials and craft one.\nYou need to place it near a girl survivor.\nYou can also tell her to follow you and place the station at desired destination." icon="ui_game_symbol_q_farm5" repeatable="false" category_key="Quest" offer="Share your knowledge." difficulty="medium">
<objective type="FetchKeep" id="hoeIron" value="1" />
<objective type="FetchKeep" id="forgedIron" value="10" />
<objective type="FetchKeep" id="bucket" value="2" />
<objective type="Craft" id="farmerBlock" value="1" />
<reward type="Quest" id="Q_Farm_E5" />
Great job on the mod Starvation team. Enjoying it very muchly