That's mostly the gist of it; having Warly be able to use the grinding mill to almost guarantee additional seeds would (arguably) make farming better, give more use to the mill, and help allies alongside it. My suggestion would be that using the mill gives a 85% chance to give an additional crop seed when fruits and veggies are deposited into it like a birdcage; this way there is still a risk associated with it, but you have a better way to farm resources. On top of the 15% risk, you still run into the penalty of not using the birdcage other than for eggs as a result, so extra care is needed to make sure the bird stays alive by manually feeding it every so often.
Warly is very dependent on vegetables that are exclusive to farming, and the only way to recycle-farm vegetables normally is to use a birdcage, of which nets you a guaranteed 1 associated crop seed with a 50% chance (correct me if I'm wrong) of dropping another, on top of an additional 50% chance to get a regular seed. This process (if you're unlucky) can result in a lot of wasted resources just to start all over again. Again, for a character that relies heavily on farming in most circumstances, this can be an issue if you want to make recipes like Moqueca, Bone Bouillon, Hot Dragon Chili Salad, or Asparagazpacho as the only true way to mitigate this issue is to build farms in bulk (which is very tedious and time-consuming task considering the resources) to come out with a large profit (even still, with a large loss of resources as a result).