The actress is luminous, alongside her look-alike brother Junior Nyong’o, Sandra Oh and Peter Dinklage, in Shakespeare’s comedy at the newly revived Delacorte Theater.

T he last time I wrote about Twelfth Night at the Public’s Delacorte Theater, I took issue with a performance that sacrificed the play’s rich ambiguities for a relentless sing-along perkiness, a too-wide smile that,