Sure but having a singular catchall for the phenomena around that taste is actually better and I would argue more discrete (wait wtf is it discrete or discreet?). Imagine if we had to describe the fundamental tastes like this:
Except that you can have savory that isn't meaty, meaty that isn't savory, and deliciousness is 100% subjective, so I'm afraid your logic for replacing 3 different English adjectives with one Japanese one is fundamentally flawed. If anything, Japanese needs to pick one definition and import some new words to make up the difference.
Or just admit that the languages work differently and that what works for Japanese doesn't work for English, and trying to make it fit just sounds pretentious.
I guess I've never put enough thought into it to feel the term was pretentious. Based on my understanding of what the term was describing, I figured that the Japanese had just come up with a good bow to put on a complex flavor that is difficult to sum up succinctly in English. Calling the flavor "meaty" is not very complete at all because really what is being described is not a meat flavor but something that often is paired with meat flavoring. Mushrooms have umami, and beef jerky, and cheddar cheese, and ghee, yet none of these things taste much of anything alike.
You're right that something can be meaty but not savory, and to your defense I should not have claimed "deliciousness" as a component of umami—that's not really a taste descriptor but a preference. I find tart green olives to be delicious (and incredibly savory) but my fiance hates them. But the point about savoriness and meatiness is that they are both just incomplete, adjacent terms to describe a particular flavor profile missing in English. Savory is probably the closest match, but even so could something be umami and not savory?