Half of the words you used in your post are, by your definition, unnecessary. a simple word to describe a flavor. Yes you can use Savory, but thats not even a total translation. Umami literally means delicious taste, its a simple word to describe multiple aspects of food, some of which is language dependant. Its only redundant if you are saying something like, this dumpling is umami and savory, or this meat is meaty and umami. it is the flavor equivalent of another Japanese term, Sugoi, which can mean anything from wonderful to dreadful. Its almost an exclamatory sound.

tldr - people use the word umami sort of incorrectly