Around 1192, there's no way you could have come up with the month though is there Smokey ?
What I find interesting about the uillean /union question is the closeness of the sounds of the two words . Even though they have different meanings, they describe the same phenomenom . But isn't an elbow a sort of a union , a joint between the upper and lower parts of the arm ? Is that a coincidence or is there any etymological (ahem) connection.
I don't think there is anything wrong with speculation about origins of songs or words - or anything else for that matter .So long as people don't try to pass their speculations off as facts .