I do not know that circuit, I do know that many circuits from uC manufacturers as Atmel/MC and ST in their Apnotes will not 100% pass the standardised Dali testers, so figure.
Some companies have very strict additional demands for the circuit such as that it should survive a wrongly inserted mains connection, so it should survive 240AC on the Dali input if the installer made a mistake.
If you want to design something for the professional market my suggestion is to buy some decent brand like Osram or Philips Dali drivers and look what is in it.
Looking briefly at the circuit, how did you come up with the 2,5V?
It is a 5V logic system, the GPIO port will be driven with 5V high output.