Sanskrit manuscripts of the Saddharmapundarika survive, from Nepal, from Gilgit and from Central Asia, and the text was probably assembled in stages between roughly the first and third centuries CE, with the verse portions generally older than the prose around them and later chapters added to an existing core. Scholars use those manuscripts. Practitioners in East Asia, for the most part, do not.
The reason is Kumarajiva. Born in Kucha, brought to Chang'an as a prisoner of state, he led a translation bureau that produced in 406 the Miaofa lianhua jing, the Lotus Sutra of the Wonderful Dharma, in twenty-eight chapters. Chinese Buddhism had earlier translations, including Dharmaraksha's of 286, and later ones followed, but Kumarajiva's displaced them all. He translated for sense and cadence rather than word by word, and the result reads as Chinese literature rather than as construed Sanskrit. Its phrases became idiom; its chapter divisions became the standard shape of the work.
The practical effect is that when a Tendai monk, a Nichiren priest or a Soka Gakkai member speaks of the Lotus Sutra, the text meant is Kumarajiva's Chinese, chanted in Sino-Japanese pronunciation, and the doctrinal vocabulary of the East Asian schools is built from his renderings rather than from the underlying Sanskrit terms. The twenty-fifth chapter, on the bodhisattva Avalokitesvara, circulated separately as its own scripture and is a principal source for the devotion to Guanyin, in China more often female than the Indian figure was. Where Kumarajiva's wording diverges from surviving Sanskrit, East Asian tradition has generally followed him.