The only accepted options in this area (unless there is a new person) are:

Teresa Merriman: teresa.gmerriman @ gmail.com Cel:315 104 1033 (has an office in Cihuatlan)

Diana Gutierrez: I can't find her email Cel: 315 107 8689 (Diana is a teacher in CECYTEJ, so might not always answer her phone in school hours).

Both are federally recognised translators (perito traductor) for any officially needed translation at any level here in Mexico. You will pay for the stamp/seal that accompanies their work but it avoids wasted time.