2021-07-23 : Although the token is attacking, it was never declared as an attacking creature (for purposes of abilities that trigger whenever a creature attacks, for example).

2021-07-23 : Delina, Wild Mage has received an update to its Oracle text. The official text is listed above. Specifically, rolling again on a result of 15–20 is optional.

2021-07-23 : You declare which player or planeswalker the token is attacking as you put it onto the battlefield. It doesn't have to be the same player or planeswalker Delina, Wild Mage is attacking.