Who decides on the final form of the ballot text?

Republic Act No. 6735 'TheInitiative and Referendum Act'

http://www.chanrobles.com/republicactno6735.htm#.UMhZ8Gd32uI

IV Final Provisions

Sec.  19. Applicability of the Omnibus ElectionCode. — The Omnibus Election Code and other election laws, not inconsistentwith the provisions of this Act, shall apply to all initiatives and referenda.

Omnibus ElectionCode - Article XVI

ec. 181. Officialballots. - Ballots for national and local offices shall be of uniform size andcolor and shall be provided at public expense. They shall be printed on paperwith watermarks or other marks that will readily distinguish the ballot paperfrom ordinary paper. Each ballot shall be in the shape of a strip with stub anddetachable coupon containing the serial number of the ballot, and a space forthe thumbmark of the voter on the detachable coupon. It shall bear at the topon the middle portion thereof the coat of arms of the Republic of thePhilippines, the words 'Official Ballot', the name of the city or themunicipality and province in which the election is held, the date of theelection, and the following notice: 'Fill out this ballot secretly insidethe voting booth. Do not put any distinctive mark on any part of thisballot.'