Please see the attached document and screenshot to understand this: 
 
The used font is written first and then Devanagari character mixed with minus 
to make the problem more obvious. 
 
The first line is how I expect the text. 
 
The second line does not render the combination of mark and base character 
correct. The mark is always moved to the left.  
 
The third line is special because Arial does not have the needed characters, 
so OOo is using a replacement for the single mark characters. It looks like 
OOo renders a dotted circle and a separate mark which gets moved to the left.  
 
I have the same problem with Khmer, but Khmer is not supported in 680m78 so I 
looked for another language with the same symptoms. In Khmer I found a 
pattern, every time anchors are defined and used to position the mark it 
fails.  
 
hth  Jens