Life cleric says when you USE a spell to restore hp, while casting goodberry doesnt restore hp, using goodberries is using a spell to restore hp becuase you can only get goodberries through casting a spell. I think this is a very specific wording because if you look at most other abilities, such as the unicorn spirit, it does specify casting a spell so I dont think that goodberry would heal other people in the aura when goodberries are eaten or when the spell is cast as the spell specifically doesn't heal people, just the use of what you get from the spell does so it makes perfect sense for goodberries and life cleric to interact given the wording.I personally do not agree with the Disciple of Life/Goodberry interaction. It seems clear to me that someone eating a goodberry did NOT cast a spell to restore hit points to a creature. That is when a goodberry heals someone. Not when the spell is cast. But if that was the intent of the class feature, then it seems to me that Unicorn Spirit should also work with Goodberry.
I think a bettr use of the uniorn spirit/life cleric ability is to use healing spirit. Then you are using a spell to heal someone multiple people a round for multiple rounds and all of them get the life cleric bonus and then those in the unicorn spirit also get healing (although here I am less confident as unicorn does specify CAST so maybe within the unicorn spirit they only get it when you cast it).
If I said I use my fly spell to cross the chasm, noone would assume I cast fly, let it expire, and cast jump to get over it. I would have had to fly over the chasm WITH the spell I said I used. Casting Goodberry never heals anyone in and of itself, so if it triggers one feature it should trigger the other. Maybe the initial casting for both features would make sense to me, or at least be more consistent.
This analogy is very strange and really not applicable as goodberries.