Hi Stephen,
At the moment, Desktop commands with Sikuli locators are the most suitable way to interact with Excel documents as well as any other desktop environment application.
The most useful command to use with Excel is Desktop_Hotkeys which can be used with various shortcuts. Some examples are found below:
1- CTRL + Key_c = copy
2- CTRL + Key_v = paste
3- CTRL + Key_s = save file
4- CTRL + Key_a = select all
5- Up / Down / Right / Left / Page_up / Page_down / Home / End = navigating inside document