Thank you for the reply. I acctually solved it by examining maps that had it in their map options, like "the Great War". Not(!) every map has that code line in it's xml file, but at least as long as the map is based on WW2V2 rules, you can add the option to limit battle rounds by adding the above code lines to the xml files, like so;
- Find map in triplea/downloadedMaps/'map name'
- in map folder open file map/games/'map name'.xml
- find code section <propertyList>
- insert following code lines like image below;
Then you should be able to freely tweak battle rounds limit.
Hope this thread is helpful to others as well