Dusting with icing 'sugar' isn't necessary, but it does make it look more like cake and less like bread with pieces of ham inside.
If you can buy Morrisons Shredded Jackfruit in water, the macros will change to just 1.3g net carbs per 1/9th slice.No refrigeration required, although I find that it tastes better when chilled.
The only way to ensure accurate measurement of ingredients is with
Metric Kitchen Scales. U.S. alternative
HERE.