I ran into the same issue but found a github somebody else had shared previously that has working macros found https://pastebin.com/6XYbdWW3 and just read through to find what you want. Mainly I used the downrank macros that look like this:
This retargets your last enemy if you don't have one targeted and will cast the Rank 1 version of Frostbolt if you're holding shift when you press the keybind you put the macro on. You can swap out Frostbolt with Fireball or any other spell you might want to cast the quicker Rank 1 version of.
