@Andreas_Hegenberg Hey Andreas, thank you for your response and for your amazing work on BTT. You made macOS 1000 times better!
So I tried “Press Context Menu Key” just now and it didn’t do anything in Chrome (tried text field and text box), Notion (App), and Slack (App).
It did work in the macOS notes app and in Safari (both of which I don’t use)
I now have my insert key bound to open Popclip which is the most reliable since it uses the clipboard but it’s not possible to add new words to it.
Then I have Shift + F13 (insert) to do cmd + shift + ; to open Spelling & Grammar.
Then I have Cmd + F13 to do “Press Context Menu Key”
And I try them 1 by 1 until one works 
I just really wish I could have a single context menu key on macOS. I used it a TON in windows to fix spelling and for other reasons but I’ve not been able to do this one mac with 1 key. I have RSI so I prefer keeping movement between keyboard and mouse to a minimum.