First, you should get the
original fonts. Open these with a picture editor. Maintain the original dimensions and character positions. For Title fonts each character must occupy an area of 13x24 pixels. For Subtitle fonts each character must occupy an area of 7x13 pixels. Please note that the brackets are used as end caps. They surround the back-slash symbol, "\". Once you have edited your fonts save them as .png files and add them to your level's "Custom Objects" folder. In your World.ini add the tags:
[World]
Title=MyTitleFont.png
Subtitle=MySubtitleFont.png
Name the files whatever you please.