This idea seems to come from a WHO report that mentioned the Bach remedies, along with other forms of complementary medicine, as examples of the kind of complementary techniques that were being used around the world.
It seems that somebody misread this passing reference as being an official statement of approval. This mistaken belief ended up being put in a book. From there, other authors have quoted the same statement to the point where the idea is quite wide spread, particularly in Spanish-speaking countries.
As far as we know there is no truth in this statement. The World Health Organisation doesn’t approve or licence any treatments, so the question should not even arise.