Unfortunately, I do not think it is at all possible to change the order of execution. I could certainly see why it would have its benefits, however, in some cases there is a way to trick the order of execution by using do after blocks. This is more so of a hackish workaround, I know, but it does work.
In terms of your collision response, I doubt it would work. One Idea I have that might be a bit hackish, I believe that the order of execution might be based on certain factors. For example, the order could be based off which behaviors were added to an actor/scene first.
One way to test this would be to put different print statements in the when created section of behaviors, then add the behaviors in a certain order. Do this same thing using a separate actor, but add them in a different order. Verify the order in which the statements were executed to confirm whether it works or doesn't.
Now, if there is somehow an upper level method in the API that can be accessed, such as an array that stores the behaviors and then executes those behaviors based off the order in the array, and you can access the method, then you might be able to use some code to modify the order yourself, again, rather hackish.
Anyway, these are just some ideas that you could run with and see what works and doesn't work. At least until a way to change the order has been implemented, whatever solution is found, would likely be worthy of a Stencylpedia article so others could take advantage of it.
