Yes, this is the code I tried the second time, since I saw that it was the old styles that had been used in the first code. However, this new code makes all my previous P1 text change to FF-Mark-Regular, meaning, I'll have to manually go through my whole site and change all of this text to P2.
I'm not sure if I'm explaining it correctly – but what I'm trying to achieve, is keeping all text exactly as it is, but changing the name of the style (i.e. P1 needs to be called P2, and vice versa). But as I've said, I'm not sure that's even remotely possible...
Just a side note: Funny, but this code also changes the font of the dropdown menu to SwissWorks, when I'm in edit mode. Is that because the menu uses whatever is set as P2?