How can I adjust sweetness without hiding the elderberry and dark rum flavour?

Expanded Explanation

Wait until the infusion has been strained before making the final sweetness adjustment. Fruit, cacao, coffee and spices change considerably during maceration, so judging the finished balance too early can lead to unnecessary sugar. Muscovado provides rich caramel depth, while honey gives a softer texture and can make the liqueur seem sweeter even at a relatively modest quantity.

If the finished drink is too dry, add a small amount of dissolved sugar syrup or mild honey, mix thoroughly and taste again after it has rested. Avoid large additions in one step. Elderberry should remain clearly identifiable, with the dark rum still contributing warmth and depth rather than disappearing beneath sweetness.

If it is already too sweet, additional unsweetened dark rum can reduce the sweetness while preserving the intended spirit character. Make small measured additions and record them. A short resting period between adjustments gives a more reliable impression of the final balance than repeated immediate tasting.