MADRID — Six months after announcing a significant easing of the naturalization process for Sephardic Jews, the Spanish government has yet to put the rules into practice, leaving many applicants for citizenship frustrated.

The change, announced in November by the foreign and justice ministers, was presented at the time as a conciliatory gesture toward Sephardic Jews, whose ancestors were expelled more than five centuries ago during the Spanish Inquisition, one of the darkest chapters in Spanish history.

Foreign Minister José Manuel García-Margallo said the time had come “to recover Spain’s silenced memory.”...