Thanks for the response, I'll try to clarify my intent and some other things:

My goal was to have my cursor's 'image index' change based on certain ingame conditions. (mouse overing something, etc.). I had been previously accomplishing this with several different 1-frame cursors and then setting them to current. I wanted to rework how I did it and started trying to use native_cursor_set_frame and native_cursor_get_frame

• "native_cursor_get_frame is like image_index in GM - it can only be between 0 and count-1. And your cursor has a single frame."
  Yes, I operated under that assumption and my cursor (or at least the sprite it is created from) doesn't have a single frame, it has multiple, unless I misunderstand what native_cursor_create_from_sprite does.
  When I use native_cursor_create_from_sprite and set its frame argument to... 2, let's say, then it correctly displays the '3rd' image in the sprite.
  It then does NOT change when I then use native_cursor_set_frame and native_cursor_get_frame after creating it and setting it as current.
   
• I did not foresee that people would try to get frame of a non-current cursor so that’s not working right.
  Even if current (which I assume you mean after using native_cursor_set?) native_cursor_set_frame and native_cursor_get_frame do not behave correctly from what I can tell. get_frame is always zero for me, and set_frame doesn't change which frame is shown.
  
  Am I misunderstanding what any of these functions do? Hopefully I was clearer this time so if I misunderstood them you could at least see what I was thinking.
  I can easily go back to my original method and get the results I wanted I think, but I just wanted to make sure I didn't misunderstand these functions and let you know if it were the case that these weren't working properly.