The same article also notes the Pirates' interest in Yeonis Cespedes, but we already knew about that, and Neal Huntington has also more or less confirmed that the Bucs won't be serious players there.
Chen is 26 and put up good numbers in his first few seasons for Chunichi. However, he had a leg injury last year that caused him to lose velocity, and he only struck out 5.1 batters per nine innings. I'd want the Pirates to be very confident about his health before I could endorse signing him, especially because his fastball appears to be his strikeout pitch. You can check out his fastball and breaking ball here.
Wada, 30, had much better numbers than Chen last year, but he apparently throws 86-87 MPH - that's not necessarily the kiss of death for a lefty, but it's something I might be a bit concerned about when determining whether his success in Japan would translate to the major leagues. His arm slot is a bit lower than most pitchers (you can watch it here), so maybe he could be a LOOGY if starting doesn't work out.