"I like Rhaegal's colors."

Translation: Rhaegalo sȳndrilloti vaoresan.

[ReinerSelb]

should be "sȳndrilloti" instead

[Noah688128]

why sȳndrilloti and not sȳndrilli?

[ElaineRosier]

I'm not sure but I think it's because colours arent declined like nouns but adjectives.
So they would follow the declension of the Noun Rhaegal (Genitive) but in plural instead. Rhaegal is 6th declension, so the genitive ends in -o (Sg), respectively -oti (Pl)

[Ctxkh1Me]

Not quite. The colors (timpa, zōbrie, kasta, qeldlie, mele) are adjectives. None of them are specified here, however.

You're correct about the genitive of Rhaegal, and sȳndrilla "color" is an Aquatic noun that declines like a Lunar noun. Here, Rhaegal is singular (only one Rhaegal) and colors is plural, so in the accusative we would have Rhaegalo sȳndrillī. But vaoresagon expects the genitive/dative form, because it's a locative applicative. So, it's sȳndrilloti because that's the genitive/dative plural form of "color."