Her parents registered her birth with the US Embassy, which issued her a US government birth cert. The Indonesian BC doesn't matter.
When her parents came back to the US in 1977, she was issued a COLB and a passport.
She had been issued a US Passport before she left Indonesia. You don't get a passport after arriving in the U.S., you must have it already to be admitted.
Now, 32 years later, she just got another passport and she only provided her COLB and that old passport.
The old U.S. passport is the proof of U.S. citizenship she needed to obtain a new passport. The COLB was irrelevant.
The COLB doesn't even list her parents but she received her brand new passport in record time just a few weeks ago.
She'd proved U.S. citizenship via an old passport, so unless the application form was messed up it should only take a few weeks. Days if you pay extra.
My sister said she only has an Indonesian long form, nothing about the Embassy issuing one. She said it's not in English so you can't read her only long form. I'll have to check again as you seem more knowledgeable than I.
The old U.S. passport is the proof of U.S. citizenship she needed to obtain a new passport. The COLB was irrelevant.
I'd wondered if that was the reason but, silly me, since 9-11 I assumed security would have been a little tighter (since she was only about 18 months old when they cam back to the US and 32 years in between.) and they would have required additional documents. But, as I said earlier, I'm not very knowledgeable about all of it.