Translation guide
Indonesia is a country name. In Japanese, it is almost always expressed as インドネシア. There is also a formal kanji name 印度尼西亜, but this is rare and literary.
Referring to the country Indonesia
The standard Japanese name for Indonesia, used in all contexts.
Indonesia is a country in Southeast Asia.
Ateji (kanji used phonetically) for Indonesia. Very rare, mainly found in historical or formal documents. The reading is the same as the katakana form.
I plan to travel to Indonesia next year.
Republic of Indonesia (formal name)