I am attempting to create a similar cake but I cannot get the “streaks” right. Suggestions?

What have you tried so far? It looks to me like maybe they used a large bristled paintbrush to paint on a luster dust/alcohol solution, or maybe they used Edible Art Paint or something like it.

I have tested dry powder dusts with amd with out alcohol. Without alcohol gets me closer but not quite.

That’s the only way I can think of that you could do it. What dusts are you using? Depending on the brand, the opacity is different, which could change the look it gives you.

I would do it by mixing petal dusts with alcohol to a water color type consistency and apply with vertical strokes, letting drips run where they may.  It's a very organic design.