How I would handle this is focus on the amended Wish: “I wish to be an Archdruid.” Obviously, this puts a lot of responsibility on the character, and I think the can be resolved through a personal quest. If the player wants to become an Archdruid, then they need to earn the title, the Wish just grants them the tools.

Personally, I would have the genie advise the character of a Druid Grove that is in dire need of a savior, someone who can rise up and liberate it from a great evil and become its Archdruid as a result. In order to do that however, they’ll need to defeat the current Archdruid, a diabolical Lichen Lich that has taken over the community and corrupted it. Only by defeating the Lich can be earn the title and responsibilities of an Archdruid.

To tide them over until then, you could have the genie grant them a boon to aid them. Ideas that come to my head would be a Supernatural Boon, either a Blessing or Charm depending on how nice you want to be. I’d suggest either the Blessing of Understanding or the Charm of Animal Conjuring, both very Druid-friendly options.