You should consider taking trip to central java or yogyakarta, I see you have interest in temple, there’s Borobudur temple and prambanan temple, those two are an amazing temple worth to see. In Yogyakarta you’ll see kraton, tamansari, etc. Central java and yogyakarta has different atmosphere of enchantment, well in Bali and Lombok you’ll dazzle by the beautiful beaches, but in central java you’ll see stories about all things cultural, from ancient sites to cultural events.
Yesterday I’ve heard about Dieng culture festival in around 4th to 6th this august, just google it (Dieng is just a few hours away from Borobudur). All I know about cultural events is there’s gonna be a lot of unique performances from local people, and it’s only held once a year (you’re right in the way for this! Haha). Don’t worry about accommodation and stuff because there’s a lot of option, from hotel, homestay, or even a hostel. if this helping, my nephew just stopped by in dieng for a few days, they stayed at Tani jiwo hostel. They come out not only just fine, but can’t stop telling about their experience there, like just can’t get enough of it. Even I still in the chat with him talking about that place, and considering myself to go there. If I had the chance I’ll go to dieng culture festival and maybe spend night there. Oh well hope this’ll inspire you to have an amazing holiday in Indonesia.