It's true that I didn't realise there were already pics of them on Danbooru but I actually got the names from Wikipedia. I know Wikipedia isn't 100% reliable, to put it nicely, but given that Tales games never have Japanese-sounding names in (e.g. Lloyd Irving, not Roido Aavingo, Cress Albane not Kuresu Arubein) unless the character is obviously based on a Japanese archetype (e.g. Suzu Fujiyabashi being a ninja), you can take it for granted that it won't be Hisuka or Shasutiru, which is how the names would be properly romanised. Shastere is just as much of a guess at Chastel, though looks far more awkward.
The subs should be out pretty soon, from Chihiro and Abyssal Chronicles, so we'll have an "official" spelling then. Anyway, their last name would be Aihiipu if accurately romanised, so come to think of it, I'm not sure where anyone's getting these romanisations from.