More than a little surprised no one has suggested Virtuoso.
It has implications of high mastery, but in its more archaic forms it also implied broad mastery; dilettante is a synonym (albeit a somewhat archaic one), and on Thesaurus.com today, "magician" is one of the favored synonyms now. It retains the implication of performance (since "virtuoso" is strongly linked to musical performance specifically), but permits a somewhat broader interpretation. Further, it would make perfect sense that you could have "Virtuosos" who are specialized in specific areas despite their overall interest in a wide variety of fields. 3e even used it as a name for a really quite strong Bard prestige class!
So...yeah. That seems like "Virtuoso" is the perfect name. It retains the right connotations, it expands on them in both archaic and modern senses in on-theme ways, and it has both the flexibility and the actual game history. It does, of course, lack a little of the implicit poetry and poignancy of "Bard" (e.g. no link to Shakespeare, "the Bard of Avon" or just "the Bard"), but there's basically no way to avoid that with a new term, so that's hardly a knock against it relative to any other choice.