Thank you for your questions concerning national parks in Austria!
This question is asked by customers many times and I hope I can clarify the situation for you.

First of all national parks do exist in Austria. They are regulated by law on the administrative level of Austrian provinces. So you would have to check the law of the 9 provinces of Austria.
In contrast aeronautical facts are issued by the federal government of Austria.

So in 2009  the federal government of Austria (CAA) asked all provinces to state their needs concerning the definition of these areas for aeronautical purposes and instructed Austro Control to remove the information from all official aeronautical publications.
Since then the governments of the provinces were asked several times (as far as I know) to state their needs so they can be reflected in Austrain federal law and continuative be published in a way used in international aviation (e.g. IAIP). Currently the restricted areas LO R 16 and LO R 18 are the only areas that are published because of environmental reasons although there is no national park defined. The Austrian federal law concerning airspace issues is usually amended once a year but until the provinces do not provide the information to the federal government this information is not published and is missing in all official products.

The Austrian AeroClub is aware of the situation too and maybe they can provide you with more details concerning this topic.

We know that for the user/pilot this situation is disadvantageous but Austro Control has to follow the instructions of the CAA of Austria.