Gave up on trying to get the GOAP algorithm to correctly apply the cost structure to competing choices, and instead I take the resulting action list and simply find the next best one based on cost.

assets/ai.json

@@ -120,6 +120,6 @@
       "collect_items",
       "use_healing"],
     "Enemy::actions":
-      ["find_enemy", "kill_enemy", "run_away", "use_healing"]
+      ["find_enemy", "run_away", "kill_enemy", "use_healing"]
   }
 }