I've read the definition and I guess it's not always as overtly negative, but that's easy to fix with one or two extra words, ie. "self-centered dilettante"

The French sense is how the word was originally used, and it can still be used that way. But the primary sense now is about the superficial nature of the person's knowledge or interest. So it's negative, but not as negative as the word OP is seeking.

I've only ever heard it used negatively; in English it has the connotation of someone who enjoys being know to do the activity but isn't invested in the activity itself; someone who isn't serious about the activity.

From looking up more usage, as it isn't a word I often hear, it seems by nature to be neutral, but context can direct it to be more positive or negative.

If I heard someone say it in conversation, it would put a lot of emphasis on the tone of the conversation to take the meaning. I'd imagine it being used more sarcastically, as it sounds like a fancy word for someone with shallow knowledge of a subject.

"John won't shut up about that trendy new art exhibit."

"Oh yeah, he's a real dilettante all of a sudden!" 😒

John had never shown interest in art before, but now that he saw it and either liked it or pretended to like it to show off his "higher appreciation of culture" than his friends now he keeps talking about it even though he doesn't know anything about art.

I wouldn't say it's impossible to use in a positive manner, but being dismissive feels more likely. If someone used it that way I'd feel I was potentially missing out on a joke at first.

Thx everyone for the clarification :)