Sql Server 2012 Extended Events for Selective Xml Indexing not showing results
Not sure what you are seeing and not seeing in the event log but it works as expected for me (version 11.0.3000).

The mistake you did with your extra path expressions is that you forgot Stuff in the path.

Testing this with the extended events and looking at the execution plan for operator Table Valued Function XML Reader ... (there should be none), I found that one extra path is enough for your queries to make it use only the index to fetch the data [4] = '/Root/Stuff/Forms' as SQL nvarchar(25). You can have [3] = '/Root/Stuff/Forms' as XQUERY 'node()' in there as well and perhaps it will make a difference or not depending on what your XML look like.

Note 1: You have mixed up the names of the columns in the index and your query. That might contribute to the problems you have with extended event.

Note 2: The events for missing selective XML indexes is generated when the query is compiled. If the query plan is used from the cache you will not see any events.