Can you provide a bit more information about how you are executing that search (in JavaScript or in the Node Browser), and what other parameters you might be providing in the search. There are different APIs to execute a search and it is not clear which one you have used.
Also, it is not quite clear from your question what the full result set should be.
You are making extensive use of wildcards. This type of search can be very locale-dependent, which can partially be seen in the different result you get for en. The reason for this is the tokenisation of both the index data as well as the request data. If the tokenisation of both does not match up exactly, there may be some expected results that you are not getting. It is worth checking what locales the individual documents you are expected have been assigned. You can see this in the node browser as part of the node properties.
If you often have to search for a particular date-like fragment of the document name, I'd recommend extracting that fragment into its own property. This not only improves the performance of the search by potentially obsoleting the use of wildcards and limiting the search scope, it can also provide far more accurate results.
