The "Acuña" name is the castilian translation of the "Cunha" portuguese name.
The first person using the Cunha name is Lorenzo Fernandez Da Cunha (1150 aprox.) a portuguese rich-man.
Lorenzo was the son of Fernando Pelaez. In october 20, 1147 Fernando participates in the Lisboa battle and receives from the King the lands of Cunha Alta and Taboa, being the first Señor de Cunha Alta y del Concejo de la Taboa.
Fernando was the son of Pelayo Gutierrez da Silva, Adelantado Mayor de Portugal.
Pelayo was the son of Gutierre Peláe, son of Pelayo Pelaez, Señor de Cisneros
Pelayo Pelaez was son of Pelayo Fruela, Infante (Prince) de Leon ans origin of the Houses and names of Acuña, Ansurez, Cisneros, Girón and Silva, very important names in Spain.
Pelayo was son of the Count Fruela Ximeno, son of the Count Ximeno Aznar.
The Count Ximeno Aznar was son of theInfante de Leon, Aznar Fruela.
Aznar Fruela was de son of the King of Asturias and Leon, Fruela II (845-875).
And I can continue until the Baltos Dinasty, in the central Europe lands the orign of the family.
There are not "skips", "gaps", etc, and when some jews arrives to Spain the origin of the Acuna Family has been established. Even more the name is "de Acuña" it means (in this case) the noble origin (de la Casa de Acuña).
If there was any suspicion about a jews origin
1 - It has not been detected by the best spanish genealogists: Luis Salazar de Castro, Francisco de Bethencourt, Sandoval, Brandon, Sousa Macedo, Brito, Garibay, and so on. 2 - There would have problems to obtain the "blood purity certificate" to be accepted as knight in ALL the spanish Cavalry Ordres. 3 - Was difficult to be appointed as Familiar of the Santo Oficio (Inquisition) a common job of several Acunas.
So, I am sorry but Acuna name is not a sephardic name. Try in other way because this is not possible to corrupt, or disguise.