Currently html does work inside text strings if they are created in the developer. However if you have a task which takes player text input and they try to use line break code ie. <br> it is ignored.
Being able to enable the player to use line break would make games that require the player to make notes or even write some of the story or give descriptions for things a means to do so without the text being a huge paragraph.
I am currently working on a game where the player writes a story based on choices the player makes and is prompted with a new situation which the player writes what happens.