I don't know what the numbers represent, but from what I've read, increasing the second digit increases the transmission length. I think the default is (0;0) and I've seen users have success with (0;30). But I think that is pretty long. The best solution is to try different numbers. If there is a particular code that gives you problems try starting with (0;5) and see if that helps. If not, increase it until it does. Then change the duration for any other keys you have trouble with.

When you experience code reception problems in a macro, keep in mind that sometimes a DELAY between commands may solve the problem as well.