This only applies to the Holos within those packs. As far as we know, only European produced packs contain 1999-2000 holos. These packs also contain 1999 holos and there’s no way of verifying.
I do not know if the Australian boxes contain 1999-2000 holos.
Got some info on a Made in the USA Base 4th Box. This box contained all Base 4th packs as seen below. The box does not contain the common indicators found in other countries however it does have some clues. Primarily the bottom of the box features only the US office info as shown below: