Your first link is broken, I got a 404.
Unclear issue, intersting however.
For me a Bust order is a request on an executed order. you ask to unwind a wind up transaction. That is always a frustration for the Exchange involved and prone to abuse in HFT so they penalize that.
Interesting, I never heard of fee for cancel/modify, as long as the order is not started you are free to do that.(Rephrased: I feel free to do it without minding that)
Unless that a limitation on small amount of cash, Put at least 25K$
?
I also understand the difference between SMART and DIRECTED. I will hypothesis that:
With Smart , IB is in charge and will decide, where and when, the order may stay pending in their pool until they found the NBBO.
Direct, IB must place the order at the place of exchange for you and they are under the rules of the exchange.