Most Thai people don't know about Elephant apple. But in all cases about trees that are in Thailand, nobody is more knowledgeable than the Thai people, so much more information can be gained from Thai language resources.
Some english resources for example will only cite "medicinal value"
but then you can go to a site like
https://medthai.com/%E0%B8%A1%E0%B8%B0%E0%B8%95%E0%B8%B2%E0%B8%94/And they will actually tell you what medicine to make, how to make, how to apply, etc.. However dosing information is usually not mentioned.. so not a complete resource.
Interesting fact is that these trees are actually eaten by elephants, so they will occur all along the routes of elephants near jungle, mountain, and especially waterfalls and fresh water.
They are especially hardy, and if you see one sprouted near the tree (a near guarantee) then pinch it out and put it in a container, it is a very attractive potted plant, that is also very hardy like Banyan.
The roots seem to have a very similar medicinal value to willow, however medthai lists number one reason to plant "Matad" (don't confuse with Mahat) as---
นำมาใช้ประกอบอาหารเพื่อรับประทานมาตั้งแต่โบราณ เช่น การทำเป็นแกงส้มมะตาด แกงคั่วมะตาด หรือนำไปทำอาหารอื่น ๆ หรือใช้ผลสดจิ้มกินกับน้ำพริก[3] กลีบชั้นในที่มีลักษณะอวบอุ้มน้ำ ใช้จิ้มกับเกลือกินได้ ให้รสหวานอมเปรี้ยวเล็กน้อย
Used as food since ancient times, cooked in the "Gaeng Kua Style" (note below), or ripe fruit is eaten with chili paste, or the petals can be eaten with salt for a sweet and sour taste."Gaeng Kua" style is when you are making a curry, first you stir fry (Kua = roast) the spices and meats before adding water/coconut milk.
I imagine to roast this harder fruit it would be chopped up finely first like how other curry pastes incorporate minced ginger, lemongrass, chili, etc.
With this amount of information available, don't be afraid to eat some ripe petals next time, but if you want to cook the ancient curry, then you might want to research some more on portions and if you are using green Matad or ripe Matad.
Sadly I only learned this much later after studying the one I had in a pot, and one of the Thai gardeners thought it was a weed in the pot and tossed it when I was away. I collected my seed from a remote national park and haven't been back since.
Heres a tree I found in North Thailand
Never seen it anywhere in the past
Any help with ID is appreciated
Thanks