Alright, let's see if I can come up with some good words to use for both these names...

Sergio is Latin for "Attendant." Relevant words might be: Zaam (Slave), Aar (Servant), Aak (Guide)

Cabezas is Spanish for "Heads." The Dovahzul word for "head" is Klov. (The plural form is Klovve.)

Since Dovah names are generally composed of three monosyllabic Words of Power(also known as rotmulaag), you'd probably want to combine some of the words I mentioned. One potential name would be Aakaarklov, "Guide Servant Head," but I personally think that Klovaakaar, "Head Guide Servant," sounds pretty great!

Yago is Hebrew for "Supplanter." This is a tricky one to translate properly. It implies a government that overthrew the previous government. Most of the canonical Dragon Language words associated with this have a negative connotation, unfortunately. Some relevant words include: Gruth (Betray), Vothaarn ( Disobedience), Tahrodiis (Traitorous). The only one that would fit nicely into a proper Dovah name would likely be Gruth.

Ortiz means "Son of Orti," and Orti can mean either "Brave/Strong" (from Latin fortis) or it can mean "Fortunate" (from Latin fortinuis). Relevant words might be: Kul (Son, also means Morally Good), Kril (Brave), Mul (Strong/Strength), Dez (Fate, for fortune).

I'd recommend keeping the word Gruth in your Dovah name, since it's the only word that would convey the meaning behind the first name Yago. Kul would be good to use too, to keep the original meaning behind Ortiz. Kril, Mul, and Dez would all work to fill the third syllable in the name. You can also mix and match the available words in whatever way you see fit, as they all carry the meaning behind parts of the original name.

Some possible names include: Kulgruthkril, "Son Betray Brave"; Gruthkuldez, "Betray Son Fate"; Krildezmul, "Brave Destiny Strength." You can also construct your own name from the Rotmulaag (Words of Power) I showed you above.

This was a fun exercise for me! I love doing things like this, and I feel like this turned out fairly well. Hope this helps!