WoW macros definitely execute from top to bottom, left to right. The first true statement that the the client reaches is what's fired off. If that first true statement directs to a spell that's on cooldown, then the macro tries to use that spell and the macro essentially fails.

I think RIFT allows you to just list a bunch of spells or abilities, and whatever is on cooldown will be skipped, but there isn't enough information from the quoted text in the first post of this thread to know whether the client will jump over spells that are on cooldown (like RIFT), or if the macro will stop when it reaches a spell on cooldown (like WoW).