1/3c Sugar is never going to dissolve in the ~one tsp liquid from the extracts, and sugar simply does not dissolve in fats - so your cocoa butter won't dissolve it either.
This is a known problem in chocolate making, both white and not... commercially sugar and/or milk powder is mixed in by a process known as conching, where the sugar is mixed into the chocolate by grinding, often for days, to the result is smooth to the tongue. Many "homemade" confections either start with premade chocolate, or add liquid to dissolve the sugar... which ends up making a fudgelike confection (you have to add other ingredients to prevent the chocolate from seizing, and end with the confection not only softer but with other flavors), some try using butter for its water content.
If the cocoa butter is just melted to or cooled to sludgy, before adding the sugar, the powdered sugar might be folded rather than mixed in and the result cool quickly enough not to settle. It still may have texture issues, though.
As for the alcohol-based aftertaste, it may be the extracts were too much for the amount of chocolate, or that your particular extracts had a heavier alcoholic taste. I believe extracts intended for candy making are different from those intended for baking, for this reason among others - they have less liquid, they are rated to higher temperatures, they balanced differently since they are less likely to be mixed into larger volumes to dilute tastes.
Many recipes start with chocolate melting discs, etc, for this reason. If you really want to make your own, or you want a flavor profile with a higher % cocoa butter and/or less sugar, you might have some success with adding cocoa butter, milk powder, and flavorings to lesser amounts of white chocolate (essentially, you'd just be using it for the amt sugar needed for the larger batch, the cocoa butter and milk powder already there would be "extras").