Who decides on the final form of the ballot text?

Referendum Act (amended date: 2018/01/03)

Article 3. The competent authority for national referendums is the Central Election Commission, which is responsible for directing and supervising municipal or county (city) election commissions. […]

Article 17. The competent authority shall make the following matters known to the public through public notice 28 days before the day of referendum:

1. The date of voting for the proposal of referendum and the times of commencement and termination of voting.

2. The serial number, main text and statement of reasons of the proposal of referendum.

3. The position papers raised by the government agencies on the proposal of referendum.

4. The scope and method of executing the right of referendum. […]

Article 18. The competent authority shall collect the matters publicized under the preceding Article and the relevant regulations on voting to compile and print the referendum bulletin, and shall deliver it to the families in the voting district 2 days before the polling day, post it at appropriate places separately, and publish it on the internet.

Legislation does not provide clear rulings in this regard. However, reading the Articles 17 and 18 of the Referendum Act, it can be assumed that the Central Election Commission is responsible for the final form of the ballot text. [The procedure for ballot text processing is not specified for mandatory referendums.]