If offense is throwing in from under its own basket, lobs the ball towards back court, and intended teammate has it touch his fingertips prior to going to the backcourt, is it a violation if offense then retrieves the ball from the backcourt?

No. The offense didn't have control in the front court so they still have the entire court to use.

Offense doesn't have to have control in the front court - only team control when the ball attains front court status. By rule there is no team control on an inbound situation.