::::::Could we avoid using terms like "ludicrous"?  I don't think any of the opinions here are ludicrous, though one opinion might be more supportable than another.  Even insupportable arguments are better opposed by reason than by characterization, in any case. 

 ::::::It's certainly true that I find the English forms of the name easier to remember.  I was unfamiliar with any of this history before I read the article, and did not have any preconceptions that "Constantine" was the natural name, but the unfamiliar Gaelic forms are a bit more difficult to parse.  However, if current reliable sources are using Gaelic forms, then readers who start here and go on to the references are going to be confused too, because they won't see "Constantine" or "Donald" (etc.).  Our job is to reflect current usage.  Here the difficulty is that common usage in popular culture is not the same as common usage in reliable sources.  Is there a relevant naming policy that can be cited?