The speech was delivered in Korean so this is a choice by a translator. I don’t speak Korean but I asked an LLM and it says …

the phrase used is "대도약" (daedoyak), which literally means "great leap forward" or "great jump forward." This is NOT "대약진" (daeyakjin), which would be the direct translation of China's "Great Leap Forward" (大跃进).

To expand a bit, even saying 대약진 _daeyakjin_ "great leap forward" wouldn't have turned many eyes, because _dae_ is just a common prefix ("great") and _yakjin_ is also a common word meaning "leap forward, push forward, improve". The word simply doesn't have the same connotation of the English phrase "Great Leap Forward", which is almost always used for the infamous Chinese movement.

If a Korean speaker wanted to talk about that Chinese movement, they'd use the full name, 대약진운동 (大跃进运动): the great leap forward movement.