Is there any specific reason to pick Java over Python?

Not really.

However, most of our developers (apart from the iOS devs, obviously) are intimately familiar with Python and are using it in our production environment.

So go with Python. Then Devs can also contribute to e2e Test Automation (faster).

Is there any specific reason to pick Java over Python?

Not really. It depends on which language you feel more comfortable with.

However, most of our developers (apart from the iOS devs, obviously) are intimately familiar with Python and are using it in our production environment.

So go with Python. Then Devs can also contribute to e2e Test Automation (faster).