Thanks Dave - the medium looks quite fine. Coco peat tends to be somewhat acidic so it could be a good from a pH standpoint, but the particles are pretty small. If pumice is available, I'd use a lot of that and maybe use something acidic as fertilizer or a top-dressing.
What I don't know is how fine, organic soils will work for azaleas in hot, humid environments over time. Have you found other azaleas growing in Indonesia? If so, see what they're planted in and how they're doing.