Can I make a Liqueur myself?

Idea:

– 1L 190 Proof Grain

– 1/3 to 1/2 Gallon of distilled water

– Around 300g sugar

– Caramel, Green Apple, and Brandy flavoring

So yield would be close to 2.5L making it 60-80 proof.

Idk if the sugar is not enough to make it sweet, or my math is wrong. I want to make it drinkable itself, and strong enough for a mixed drink.