* PRINCESS CARABOO (PG, Columbia TriStar Home Video). A young woman found wandering the countryside in 19th-century England appears to be a lost princess from the Orient -- or is she? The aristocrats who adopt her think so; skeptics, like their foreign butler, think not. It's up to a local reporter to discover the truth about the would-be royal in this charming tale based on a true story. While not action-packed, the film engages viewers with its rich setting and costumes and its host of convincing stars, including Phoebe Cates as the non-English-speaking princess, Stephen Rea (''The Crying Game'') as the reporter, and Kevin Kline as the doubting manservant.