When an orphaned, mixed race American teen is sent to live with his Holocaust survivor grandmother in Sydney, he must learn to overcome his own racial and cultural prejudices and accept his rich family heritage.

You are right. This is a story I was thinking of developing about the time I got the first cancer - six years ago. I found the logline and thought I'd put it up for comment. I forgot details of the outer journey. It was team sport to the rescue, for sure.

There's a lot - maybe too much - to take in for the reader... and yet there's not enough story.
The inciting incident is clear: hero is thrown out of the comfort zone and becomes fish out of water.

But what follows is purely an indication of an Inner Journey, not of a screen story. "to overcome his own racial and cultural prejudices and accept his rich family heritage" is not a story people buy expensive movie tickets for to see. Find (or include in the logline) the Outer Journey that is the vehicle for this theme and you may have more luck.

In terms of character, you may have layered just a little too much for the reader's 25 word attention span: an orphaned, mixed race, racially and culturally prejudiced American teen... Ask yourself: which parts are essential to the story?

Perhaps you can leave out the 'orphaned' because I'm assuming this is the cause of the inciting incident. And all that matters here is that the teenager is thrown into a new world. At this stage we don't need to know why.