There appears to be some confusion here regarding how right modifiers are handled by the WoW, and how they should be handled by Fogyreef's parser.

In Shadewalker's example...

he's got a bunch of Right Alt+Numpad, and Right Ctrl+Numpad. Assuming these are Key Combinations assigned to WoW Macros (which seems to be implied here) WoW will treat every single one of these, when bound, as simply Alt+Numpad, and Ctrl+Numpad. You can try it yourself. Go into the Key Bindings screen and try binding something to Right Ctrl+Num / and see what comes out. It'll be Ctrl+Num /. The only way for you to separately use left and right modifiers with WoW Macros is for the macro to use [mod:l___] and [mod:r___] as part of the same WoW Macro.

In summary, what I would recommend to Fogyreef for this parser is to strip the Right out of the Key Combo. Because Left and Right modifiers conflict, in every single case you can parse.

I don't think I have a PC that can operate this sheet to give any other advice, since it doesn't work in either OpenOffice or LibreOffice

Something I'm not really clear on (being unable to see for myself atm) is how many pools of hotkeys/keycombos this is using. WoW Macros for example do not conflict with ISBoxer Hotkeys. Hotkeys bound in the game really only conflict with other Hotkeys bound in or built into the game (yes this might also mean Alt+F4 being interpreted by the game as a hotkey to close the window, not just the hotkeys the game lists in the Key Bindings window...). I would probably not list any outputs (Key Combinations, meaning things that get sent to the game and are interpreted by the game) next to any inputs (ISBoxer Hotkeys, meaning things that ISBoxer will interpret, potentially resulting in an output...). Inputs and Outputs never conflict. Just Inputs vs Inputs (ISBoxer Hotkeys vs each other), and Outputs vs Outputs (Game's Hotkeys vs each other).