I'm pretty sure the writers intended the Robin in Titans to be Dick Grayson for a couple of reasons:
- in the episode where the little Larry guy is there and going thru Robin's head, the guy's actual name is Dick Grayson spelled backwards, possibly a nod to Dick
- the much debated Robin-Starfire angle. If the show's writers were really sticking to the Wolfman/Perez run in the comics, this would have meant, the Robin in the show was Dick, and not Tim
- the costume was closer to Dick's color scheme in Batman:TAS, another possible hint
- season 2 premiere when Starfire is catapulted to a possible future, she's saved from that Chronos character by Nightwing who reply to her inquiry about "Robin?" by saying "Havent used that name in a long time" Sounds like our boy Dick to me
As for Titans not being part of the DCAU, I dont the writers would have goofed and let Batman mention them on purpose. How they fit in is the only question I have, unless the producers and writers have said specifically otherwise somewhere. If I missed anything, plz let me know. Thanks for listening.............