Is it possible to change "Rapat tersebut " in the second paragraph to "Rapat ini " ?
What is the root of word "dihadiri"? I can't find it in my dictionary

Yep, you can change it into 'rapat ini' :)

The root is hadir = attend
Di-hadir-i

Kementerian Koordinator Bidang Kemaritiman menggelar rapat koordinasi.
해양분야 조정부는 조정회의를 열었다

Rapat tersebut dihadiri para menteri dari sektor perhubungan, pariwisata, energi, serta kelautan dan perikanan.
언급된 회의에는 교통, 관광, 에너지, 해양과 수산분야 모든 장관이 참석했다.

Menteri Koordinator Bidang Kemaritiman, Luhut Binsar Pandjaitan menegaskan keinginannya agar tak ada penenggelaman kapal tahun ini.

해양분야 조정부 장관인 Luhut Binsar Pandjaitan는 이번 해에는 배를 침몰시키지 않겠다는 희망을 명확히 밝혔다.

번역이 정확한가요? Apakah terjemahannya tepat?
Is it possible to change "Rapat tersebut " in the second paragraph to "Rapat ini " ? Yes, but "Rapat tersebut" is better and more coherence to the previous sentence.

What is the root of word "dihadiri"? I can't find it in my dictionary.
"Dihadiri" means was attended.