Theater Ninjas and CPT animate a mud baby...by Christine Howey...When children are stressed, they often resort to creating imaginary friends or escaping into stories populated with anthropomorphic animals and goblins. That's exactly what a 10-year-old girl does in Anna Bella Eema, the fascinating but ultimately frustrating play now at Cleveland Public Theatre. This co-production with Theater Ninjas features a torrent of finely crafted narration, handled mostly by both the youngster named Anna Bella and her mother Irene. Playwright Lisa D'Amour has a fine touch when it comes to speeches…