Inside the Common Button Style class in “Properties” have a option to select the “Normal Hovered Text Style”, “Selected Text Style” and “Selected Hovered Text Style” (image below)
But doesn’t matter what type of Text Style I select for those button states, the button when hovered don’t change to the correct text style.
At 57:12 in this video from Unreal YouTube channel, Mike Prinke comment that maybe it need a bit of extra C++ to make them work with the buttons 
Little to none documentation about Common UI Plugin online, but I found this article by Ben UI, and he said:
“The weird thing is that out of the box, UCommonButtonBase will apply the defined brush styles to itself when the state changes, but it won’t apply the corresponding text style to anything inside it. To make your text change to the correct text appearance, create a subclass of UCommonButtonBase and override the NativeOnCurrentTextStyleChanged() function and use the class returned by CurrentTextStyleClass().”
So the question is:
Is that the final version of the Common UI plugin? The only way to apply common button text style is to use C++? Even when the option is exposed in the plugin class window 
Engine version: 5.0.3
Plugin version: 1.0
