It should really come as no surprise that bilingual ballots have had no effect on Hispanic voter turnout, because in fact they should almost never be necessary. In order to vote, one must be a citizen, and in order to become a citizen one must be proficient in English. We require immigrants to learn English before they naturalize because English is the common language of our nation, and a person who can't understand English will not be able to participate in the political community in any but the most marginal capacity. The overwhelming majority of American political discourse is inaccessible to a person who does not speak English. That's why we test immigrants on their knowledge of English before we grant them citizenship.
Bilingual ballots are an expensive burden on state and local governments.
It has had to produce new voting machines because its old machines could not accommodate the required Chinese characters. California also spends a lot on bilingual ballots. Los Angeles County has to produce sample ballots in English, Chinese, Tagalog, Japanese, Vietnamese, and Spanish. Sometimes, the bilingual ballot requirements are downright silly. Inyo County, California, has been targeted as needing bilingual voting services, but has never had any requests for such services.