English or Bahasa Indonesia?

So.... Kahya needs speech therapy. We went for evaluation with Dr. Ira at Klinik Pela 9 last wednesday, and she confirmed that Kahya needs more stimulation to push him to talk more. She, and the psychologist Ibu Anne, suggested that Kahya does speech therapy for 2 times a week.

Now, I am debating whether to do it in English or Bahasa Indonesia. We have a really good Bahasa Indonesia therapist, but since Kakak Nugra is now speaking mostly in English, I wonder if it is wiser to do it in English.

I googled and found this good site about early speech and language development:

http://mommyspeechtherapy.com/

The author is a mother of two children who is also a speech pathologist. The sites contain exercises and tips that you can do at home.