So unfortunately that isnt going to work. The htmlText is passed off to the host framework and it then processes it. So at that stage it has nothing to do with haxeui anymore. Even the tags that you can use in htmlText are going to vary from one framework to another. Which framework are you targeting?
Right, so with haxeui, haxeui styles only apply to haxeui components… It doesnt apply to the host framework (at all). So if, for example, you wanted to style an openfl sprite with haxeui then you wont be able to, not without creating a haxeui component - in reality haxeui components (in openfl) end up as sprites so technically you can style a sprite, but you defo cant style openfl .htmltext with haxeui styles.
The htmlText code above using <font ...> should work for you, i know openfl supports that