You choose which player or planeswalker the Bird token is attacking. It doesn't have to be attacking the same player or planeswalker that Falconer Adept is attacking.

Although the Bird is an attacking creature, it was never declared as an attacking creature. This means that abilities that trigger whenever a creature attacks won't trigger when it enters the battlefield attacking.

Any effects that say that the Bird can't attack (such as that of Propaganda) affect only the declaration of attackers. They won't stop the Bird token from entering the battlefield attacking.