You can trade them for GJC when they become available and use that to purchase whatever you want.
You can purchase the improved pass with GE and then, after selling your coupons when they become available obtain GE with that or whatever you wish.
This was already clear from the start of the 3rd pass when we announced the token system.
The tokens exchange for the standard battle pass. Not the improved one. For the standard pass, levels are purchased individually.
The improved pass comes with the +150 points as standard.