Thanks. I understand 祝日 means public holiday. Is it a public holiday in Japan? I believe Japan is not really a Christian country as such.
I’ve also noticed that the Japanese translation of St Patrick in your given examples are not the same as the one I’ve got. Yours seems to have derived from the English language.
You can go to Wikipedia and search for St. Patrick's Day, and then click on the Japanese translation (聖パトリックの祝日 - Wikipedia) and you will jump to the Japanese page where you will get the most common Japanese translation (hint: it should show above, and it should be identical to the first translation Bentenmusume-san showed you).
would also be readily understood.
That the saints have Latin names, which are also transliterated into Japanese, is not strange. It doesn't mean those katana-Latin names are the most common, or the most easily understood. In the case of St. Patrick, I would guess that since this legend was brought to Japan by the Irish diaspora, it would be surprising if it arrived in any format other than the anglicized version.
It is not a public holiday in Japan, but most people in the major cities will have a vague awareness of it. In the main centers, it will be impossible to escape it.