Hi,
I understand, but when you copy the data from pagemaker file in clipboard and paste it in indesign it works absolutely fine, then why not opening the pagemaker file ?
If you address this to your developer team they could help us in no time, because i have noticed that when you try to open the pagemaker file it applies the default paragraph styles, Is there any way that we could stop applying these default styles are defined for the latin languages and not for the Indic languages, that's what it causing the issue.