Why did the storm dragon's name change from Verudora to Veldora in the anime?
The japanese writing system doesn't have a symbol for just the l sound. The closest they have are the symbols in the r column in the kana table. The u row is most often used when the vowel is silent. So you end up with ru: ル. Which means that if you ask someone to write Veldora in katakana they would effectively write Verudora.

However when translating to a latin alphabet and you only have the katakana to base yourself on you must try and divine what the author wanted with the name. Official translators can ask the author though sometimes there is a delay with the reply. So the translators have to go with something until they got the official answer back.