I’m afraid I am completely unqualified to answer this beyond that Irene’s reign was a very messy one, ending with a rebellion against her. Her own son (the legal heir to the throne for who she was originally just regent) also rebelled against her earlier, and she had his eyes put out. It seems to me like Irene specifically was just absolutely ruthless enough to get past whatever societal rules may have been levelled against her
It’s actually in England, although funnily enough the part of England it’s in is called Cumbria, which has the same origin as the Welsh for Wales “Cymru”. So it’s sort of in Wales, just not the Wales that we call Wales in English.
Anyway it’s Old English torr, Middle Welsh penn, and Danish hoh. And like many British place names the pronunciation is not what you would expect at all at first glance. It’s “tra-pen-uh”