I am hoping someone can help me this issue I have. I’m getting married in my home country later this year to my Taiwanese girlfriend. The registration office back home is saying that I need to get an official letter from Taiwan stating that I have never been married here in Taiwan before.
This seems to be how people from US should do. You could check with the Irish authority whether a similar way with TECO is acceptable, and with TECO if they authenticate that kind of document.
Alternatively, the Irish Commissioner of Oaths could notarize a statement which states that you are free to marry. Another option would be to schedule a notary appointment at the U.S. Embassy Dublin and we can notarize an affidavit stating that you are free to marry ($50USD). We suggest you also check with the authority who will be marrying you if this option is acceptable.