What did you mean by highlighting doesn't work on mobile versions? Did you meant the bold tag or something else?
Highlighting and adding the bold tags work. I was specifically saying you cannot highlight a text and then add the option to change colour. If you try it with other bbcode tags, it will be applied to the highlighted text, but when trying to change colour the tags show up in front of the text and not around it.
You can try it on your mobile device to see how it displays.