Each of the characters who have been captured by either the Lonfa Dea or the Nha Pirtue Research Institute have unique identification codes. There are two different conventions for the codes and for how I determined them.
Lonfa Dea uses a four-character code consisting of one letter and a string of three numbers. I used Anna's host body number (A012) as stated in Tales of Symphonia canon as the basis for these. For the codes, I selected the first letter of their given names and then three digits from the hex code in the characters' canon image colors:
M653: M for Makoto, hex code #65AB31.
I003: I for Izumi, hex code #BBDBF3 (I used 0s as placeholders).
L652: L for Leo, hex code #ED6D52.
M006: M for Mika, hex code #006A6C.
K900: K for Koga, hex code #C9CACA.
K893: K for Kaname, hex code #89C3EB.
R149: R for Ruka. I used Ruka's height (149cm) for this because she doesn't have an image color.
M300: M for Mademoiselle. I used Shu's image color, hex code #E3ACAE.
Nha Pirtue uses a six-character ID code consisting of two letter, three numbers, a dash, and one final letter. This mimics the summon spirit Aska's ID as stated in Tales of Phantasia canon, when he was captured by researchers and experimented on before the events of the game. Because the Institute conducts research primarily on summon spirits, I wanted to draw this little easter egg parallel between the two. For each ID, I used the first letter of the character's family name, the first letter of a motif associated with them, a goroawase kotoba representing yet another motif, and finally the first letter of their given name:
MR116-C: M for Morisawa; R for Red; 116 for Hero (a slight deviation from the actual goroawase kotoba); and C for Chiaki
AP294-M: A for Ayase; P for Phantom; 294 for Ningyo (meaning mermaid in Japanese); and M for Mayoi
The conlang in this AU is based on Hymmnos, a conlang created for the Ar Tonelico JRPG series. One of the primary composers and singers for the series, Shikata Akiko, has actually composed and sung music for the Tales of Symphonia OVA series. I've once seen it theorized that one of those songs, Inori no Kanata, actually uses Hymmnos in its intro, and that therefore Hymmnos could be the Angelic Language, or at least similar or related to it. It's stuck in my head for probably a decade now, and I really love that headcanon, so I decided to make use of it here!
All of the character songs for the series are therefore songs borrowed from the Ar Tonelico series. Translations for the songs can be found here. Place names and the forebearers of this world too are taken from Hymmnos. The translations are as follows:
Li Sphaela: the universe
Ar Siance: the (only) holy land
Ar Titia: the (only) good will
El Shefra: the creation of the world
Chyet Jue: chosen water (as by the hand of god)
Cecet: shield
Firanzia: end of the world, end of an era
Dius Meta: divine mountainous region
Implanta: tree of god
Dius Varda: large, divine tree (as in Implanta)
Arrya oz Quesa: the arrow of thunder
So Fatele: "father figure"
Nene Giz: "without fear"
An Zweie: "shared sincerity"
Aje Merfa: new wish
Sos Grandee: "for the sake of your forebearer"
Deu Apea: "thusly blessed"
Dauane Lyuma: "star of dawn"
Diasee: child of divinity
Maya: magic
Lequera: good person
Denera: evil being
Lonfa Dea: "with the soul"
Nha Pirtue: "summon (a) spirit"