UHHHHH Barry was pretty much around for Crisis on Infinite Earths and that was it. Technically he was present for about half of Final Crisis too but since everything was hectic during that time, I doubt his perception of Dick as Nightwing would be anything more than "oh Dick is Nightwing now". Also I'm going slightly off of Blackest Night, since Barry at Bruce's grave says he always liked Robin and Hal has to correct him that the Robin now is a different one than Dick.

IDK either way I doubt he knows much of Dick as Nightwing either. The downside of being dead for like 20 years. :c