Well here I want to suggest couple of ideas about their reproduction:
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They like amethyst shards, so maybe they should breed through amethyst block to make it more expensive
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They could breed like villagers, not like any other mobs. That means not just right-clicking them with item, but they will take dropped blocks and spend about ~10 of them to be able to breed.
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main idea. Idk if this will be vanilla-like or no, but what about adding specific animation while breeding? Like the real frogs when they expand their vocal sacs to attract mates. Frog sounds (or music) should fit well. So the only two breeding will make the sounds.
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Not sure how to make ribbit certain profession: if it is born feature, so maybe some blocks nearby breeding parents could affect with some chance the profession of the offspring.
Like brewing station for sorcerer,
barrel for fisher dude
composter for flower ribbit
and for traveler/trader something like shulkerbox (bc it is movable chest....) or just a chest or a cake (bc I met the cake in it's house). Not sure about this one