I just felt the need to write this down.
Soma's name is supposed to be translated as Soma Kurusu. Translators just preferred to use the Cruz surname since it sounds the same and it refers to the Cross. I know of another anime/videogame character with a Kurusu surname but of different kanji for "su".
From my experience with the Castlevania localizations, I tend to view the Japanese original as canon.
The English and Japanese versions both give him a meaningful name.
"Cruz"="Cross", to establish that he's a better person than Dracula. While I am uncertain if the localization team was aware of this "Soma" is a drug in Aldous Huxley's iconic dystopian novel
Brave New World.
Huxley.net points out the word has 4 meanings:
1. A plant, or the intoxicating juice of the plant, used in ancient Indian religious ceremonies. Inevitably, given the Indian tradition, the plant and its juice were personified as a god, Soma.
2. The imaginary "ideal pleasure drug" in Aldous Huxley's novel Brave New World (1932). Its chemistry and pharmacology are undefined. As described, the drug resembles a hangoverless tranquilliser or an opiate.
3. "Soma" is the most common brand name of the muscle-relaxant carisoprodol. [...] Soma/carisoprodol is broken down in the body into the active metabolite meprobamate. Meprobamate is a Schedule IV sedative-hypnotic, an anticonvulsant and anxiolytic muscle relaxant. It was first marketed in the USA from 1955 under the brand name Miltown as an anti-anxiety agent. The "miracle drug" of its era, Miltown was immortalised by the Rolling Stones as "Mother's Little Helper".
4. The body of an animal or plant excluding the germ cells.
Presumably, the 3rd or 4th definition would be more fitting -- demonstrating his more relaxed attitude and emotions (which seldom get the better of him in-game, unlike Mathias who was more or less ruled entirely by his emotions), or the definition of "the whole body" to indicate his status as the One True Heir to Dracula's legacy.
And, as the Castlevania wiki notes:
His Japanese name is Kurusu Sōma (来須蒼真); Sōma is his given name. The kanji that compose his name mean, in order, 'come/next' (kuru), 'by all means' (su), 'pale/blue' (sō), 'truth/reality' (ma). Taken together, the name hints that he is the true inheritor of Dracula's power, and will definitely receive them. The kanji for 'pale', interestingly, is also used as a euphemism for being inexperienced or unripe. [This hints that] Soma has not yet reached his full potential.
No matter how you slice it, his name has plot relevant meaning.
AND I LOVE THAT.