I can tell you that I had orders with GAT parameter that were designed to go off during halt periods. They were simply executed when the market re-opened.
I'm unsure how things would go for submitting during a halt. As always with stuff like this, write a test and wait for conditions. Asking support for this is a lottery, you're likely to get a random answer that is just a guess.
For other instances you will just wait for 154 in your error handler and resubmit again and again. Or go fancy and read the halt times via some interface and sleep until that.