Solution to #4: The Manifest

    The picture of the shipping manifest emphasizes the importance of the source and destination of each item. From the text, you can determine that the flags on the tea bags belong to the countries they are sourced from, and the names on each mug removes any ambiguity in the flags (some of them could correspond to multiple countries).
    The destinations, however, are only hinted at by the phrase "customize the mugs to the buyers' tastes". The text on each mug has a strange visual gimmick, some of them mirroring the flags which to this point may seem to be a strangely unnecessary addition to the puzzle. Keeping in mind that these customizations were made for the respective buyers, you may apply each mug's visual gimmick to its flag and discover that they create the flag of a new country. The following transformations occur:
    Indonesia to Poland
    New Zealand to Australia
    Lithuania to Myanmar
    France to Thailand
    Italy to Ireland
    Entering any of these destination countries as answers gives you a vague confirmation of your work. The final piece of the puzzle lies in the phrase "we had to assure the boss that the exact quantities would end up in their destinations". If you look in the name of each destination country at its corresponding quantity (e.g. reading the seventh letter of Australia) you will produce the letters which spell the answer: "plane".

PLANE