The way I read the two events, you will never get Colonnade points since buying an estate is not buying an action. Estate becomes action when it becomes yours, but you cannot buy something that is already yours, so the condition on Colonnade "When you buy an Action card,..." is not satisfied. You are buying a non-action card, which becomes an action card upon you gaining it.
edit: I stand corrected per tufftaeh's message below. There is a rule clarification about Colonnade in the wiki, dealing specifically with this case.