For those who have adjusted the advanced font settings before, you might want to save your current settings before trying the the new interface. The settings are stored in the "Kobo eReader.conf" file. Look in the "Reading" for lines like
Code:
readingFontSharpness\Georgia=@Variant(\0\0\0\x87\xbd\x88\x88\x89)
readingFontWeight\Georgia="@Variant(\0\0\0\x87=\xcc\xcc\xcd)"
There should be two lines for each font that has been adjusted. Putting these back in the config file after a change should restore the adjustment you had before.
Also, the new method still writes both lines.