Choicescript doesn’t support the += operator. And Im not sure but I don’t think you can use *set like that. Although you do have a command called *setref.
I don’t understand why you would like to complicate things like that. The use cases for arrays are the same. The new command just makes it easier to create arrays. Becareful not to use it just because and make things more complicated without an actual gain.
If you’re going about using arrays to simulate objects than you might check these out: