[IkuzeMinna]

Originally Posted by Deacon Blues

They spelled her name Quaterine? Oh good lord this naming system is getting effing annoying. Here's a thought. The Gundam pilots that we know of are all apparently on Mars. Helloooooo Martian birth. ?

Martian birth ftw! Let's leave it at that, for my sanity's sake. xD

As for the spelling of names, I'd like to add some information on this matter.
First about the origin of the name. The name Katherine is originated from Greek, καθαρός (katharos), which means 'pure' or 'clean'. The spelling Katharine (with a middle a) was more common in the past and is currently more popular in the United States than in Britain. The form Catherine, corresponding with the French version, is also common in English. Less common variants in English include Katheryn, Kathryn, Katharyn, Katherin, Catharine, and Cathryn. Diminutives include Katie, Katy, Kate, Kathy, Kath, Kay, Kat, Katya, Katyusha, Kitty, Kit, Kasia and others.
Languages that don't feature a 'th', like German, will usually leave out the 'h' in the spelling and use i.e. Katarina or Katrin as localized forms.

As for pronouncing the name Catherine, English will usually pronounce it with a 'th' (like think), whereas French for example, will pronounce it with just a 't', like with Marie-Catherine d'Aulnoy.
From what Deacon has said there are two spellings in Japanese for the name Katherine. One is カトリーヌ (katoriinu) and the other キャサリン (kyasarin).

With all this in mind, how many 'Katherines' do we have in GW? We have Quatre's mother, Relena's mother, Trowa's sister, Quatre's sister and Sally's daughter. wtf Sumizawa. Since there's enough variety, all of them should get a different spelling, right? Based on phonetic, here's how I'd name them:

- 'Quatrine' for Quatre's mother. I'm almost sure her name is spelled カトリーヌ (katoriinu), hence sounding like 'katrin' (French pronunciation). Numerical theme naming applies because Quatre got his name from her and because quatre is four in French.

- 'Katrina' for Relena's mother. My subs give me 'Katrina' but Weridge clearly says 'katerina' which can easily be written as 'Katherina' but whatev.

- 'Catherine' for Trowa's sis. The reason it's with C and not K would be familiarity and funfacts. Obviously it's pronounced the English way, namely as キャサリン (kyasarin) (like Catherine Zeta Jones). Plus, Bloom sounds pretty English. But Catherine is originally the French way of writing it and since her bro's name Trowa derives from trois it fits.

- 'Kathy' for Sally's daughter. Sally is half American so original English spelling for her kid.

- And last but not least, 'Quaterine' for Quatre's sis. Again, it's written カトリーヌ (katoriinu) which should sound like 'katrin' (French). In this case numerical theme naming applies because of generation xerox. Heero stays Heero, Duo becomes Duo Jr. and Trowa Barton becomes Trowa Phobos. So Quatre ought to be Quatrine.

These are my humble two cents. I hope this helps somehow.