The Collection is such a large one that the 2178 items currently available for online listening is just a small fraction of it; I can't find any of the Irish field recordings there, but since the collection is searchable by title only it is easy to miss things. I expect that more recordings will be added online in time, so we may as well just enjoy the riches already on show while we wait for more to arrive.
This kind of thing is one of the glories of the internet; otherwise inaccessible collections are being made freely available so that we can all enjoy the treasures preserved in libraries and museums.
Well done to UCLA Ethnomusiclogy Department, and I look forward to seeing many other institutions following their example.
Matthew Edwards