Changing colors in highlighted text is very time consuming in Acrobat X pro. You have to highlight the text, right click properties, choose the color, then determine whether to keep it as the default color.
Is there a keyboard shortcut that can be set-up to minimize the hassle. So I can just press (eg. Ctrl+Shift+B) for blue highlights or (eg. Ctrl+Shift+O) for orange?
You can make custom stamps, and then add the custom stamp to the quick bar.
I found out that you can use Ctrl+E to have the highlight toolbar pop-up and select from their... makes it somewhat easier
I often wonder how inefficient and user unfriendly a leading and most expensive software can be. What are all those user-usability teams doing?
"Is there a keyboard shortcut that can be set-up to minimize the hassle?"
No, and there is no shortcut editor too…
If you're interested I've developed a (paid-for) tool that allows you to quicky switch between highlighting colors, and while it's not possible to assign them direct keyboard shortcuts I could add them to the application's menu and assign keyboard accelerators to them, so they can be accessed with a combination of keys.
You can find it here: https://www.try67.com/tool/acrobat-reader-quickly-switch-between-highlighter-colors
Not really what you're hoping for, but if you use your Properties Bar, you'll have the color options/properties for the highlighter (or other objects that are selected) right there without multiple clicks. Opening the Properties Bar is a quick Ctrl+E. Mine is open at all times.