Having Wandering Traders randomly spawn in and have themselves or their Llamas destroy crops is annoying enough as it is
But having the Feather Falling 4 enchant prevent destruction of crops simply by landing from them from a height would be wonderful.
Frost Walker II has neat little extra perks such as Magma Block and Campfire immunity, not just the ability to freeze the water as you are walking on it, why shouldn't Feather Falling 4 have the perk of not ruining crops? it is after all reducing fall damage which strongly implies a reduced impact on landing.
Feather Falling 2+ should mean jumping on crops does not break them, or short falls, 3+ for medium falls, 4 for big falls.
Slow falling potion should be the same if it has levels (I never use it).
That works too
There are some falls not even Feather Falling IV on boots and Protection IV on all armour plates can save you from, if they did, it'd make the game too easy, personally I think these enchantments are fine as is, and do not require any buff in terms of damage taken, despite the frustrations people have fighting the Warden which by all rights they should be avoiding, as it is their own fault if they spawn one in Overworld, 3 warnings is generous. Levitation to extreme heights from fighting Shulker's in End? potions of slow falling exist for extreme heights, if players refuse to make them, that is their problem.
But Feather Falling having one extra perk for not damaging farmlands? I got no problem with that,
it's not directly related to combat so I do not see what imbalances could arise from this.