Is there a way to create a custom keyboard shortcut in OSX?

Solution 1:

This may be a viable solution, you'll have to give it a try and see:

• This answer uses Safari as the browser, change as needed.
• The Service¹ was named Collaborator Keystroke, change as wanted.
• The keyboard shortcut assigned to the Service is ^`, change as wanted.

For the Automator Service¹:

Use the image below for the settings.

ApplesScript code:

tell application "System Events" to keystroke "]" using command down

For System Preferences > Keyboard > Shortcuts > Services:

Note: Sometimes with an Automator Service¹ and assigning a keyboard shortcut, you may first have to trigger it from the target App's Services menu one time. From then on the keyboard shortcut should work normally.

_{¹ In macOS Mojave an Automator Service is called a Quick Action.}