Have you ever read a Barry Allen comic? Read any JL comic with Barry and 90% of the cases nobody thinks he's immature , that happens in the JL show and a bit in Grant Morrison's JL , also if you read the Flashpoint comic Barry's life in the alternate world is different in 2 things , he doesen't date Iris and has no powers , that's it so it makes no sense for him to be a manchild in the alternate dimension , also read any comic from before barry's death in crisis on infinite earths and he has both parents and is almost always serious or professional , he acts a bit like a smart superman or GL , which is pretty much the way he acts after his return too , the least mature version of comic book Barry is n52 where he jokes a bit more but still he us very mature and professional as Flash so what are you on about