In India, inter-religious marriages are possible under the Special Marriage Act -1954 if the ceremony is performed in Indian territory or at an Indian High Commission or consulate in a foreign territory. This can be legally validated.
Technically you can get married in Indonesia (regulated by Islamic law) but to get it legalised, issues with inhertence and divorce are very difficult and complex due to absence of legal regulations for inter-religious marriages. Some experts interpert this lacunae as the prohibition of such marriages in Indonesia (https://www.loc.gov/law/help/religious-marriage.php).
So, it is not very easy, before you proceed, think about the circumstances that have led to you to be in this position. What are the girl and the family doing in Indonesia, are there other motives to approve this marriage other than true love. Have you met the girl and family in person? What are the views of your family?
indians in Inter-faith marriages need a huge commitment from both parties, there will be testing times when it comes to financing, starting a new home, going to functions on both sides etc. In your case, the girl is a foreigner, this would add more potential issues. Please think clearly, if the love between you two is strong and you wish to go ahead with the union, you request them to come to India. If not, to have this union in Indonesia, you have to think about conversion and then proceed.