Actuals, where the imprest holder accounts for every penny have always been impossible to administer.
Example go out for an evening meal with crew. You have meal (allowable) with a couple of beers ( not allowable) and service charge (?). Everyone has different. The only way to work it is to ask for separate bills and have the bills broken down into allowable / none allowable items.
Now try repeating this exercise in Mandarin.
The following morning take these multiple pieces of paper to the imprest officer (co-pilot?), after all he has no other duties and when he has them sorted he can discuss any issues with the captain on the flight deck. After all they have nothing else to do.
The only way to account for every penny is to use something like the F1771.
All crew members are issued with money from accounts and they keep all their own receipts. Every week or two they go to Admin wing and explain their own expenditure.
This system is a little time consuming for crew members but complex for accounts, thats why they don't like it