It seems to me that the Japanese people who wrote these stories know enough English (or possible some other European language) to know whether they wanted his name to be Veld or Verdot. Some names just don't transliterate into Japanese particularly well. It wouldn't be hard for someone to look at a transliteration of my name and thing it was a different name, but surely the author would know which name they intended.
Sometimes there's inconsistencies even within Japanese media. Edward is "Gilbert" or "Gilbart" depending where you look. Zack was "Zax" in Ehrgeiz (probably correct), and "Zack's" in a few other places (yeah, really). Final Fantasy Art Museum were a set of cards made for Japanese markets and include English titles on all of them: Engrish and obviously incorrect romanisations abound.
So I guess it depends whether the people who came up with the name get asked about origins when they're making guidebooks and
really want to put in some English names to be cool.
In the Advent Children Reunion Files, they use "Verdot" with the character portraits, and I feel like that these names were probably supplied on the Japanese side, while the translator didn't pay attention/know about them when they translated their passages. The names given with the portraits match those in the 10th Anniversary Ultimania, and the other big thing that indicates this is the two 短銃 Turks get translated as "Gun" and "Two Guns". I doubt the translator would have had the context that the male one used dual pistols.