In the standard UI we are able to use HTML tags to achieve formatting of field level guidance. I don't believe this has ever been a documented feature - but it has worked for many years and in use at RBS.
E.g </br> tag in the field guidance text would achieve a line break.
In the TFUI these HTML tags are ignored and the HTML code is instead displayed. There doesn't seem to be any option to format field level guidance now.
|Component||End User UI|
|Priority||High - Critical|