We found one bug in the functionality of converting to pdf:
A document has some compatibility options which affects line spacing, but you don’t take them into account while converting (as far as I could find out).
word/settings.xml:
<w:compat>
<w:noLeading />
<w:suppressTopSpacingWP />
<w:compatSetting w:name="compatibilityMode" w:uri="http://schemas.microsoft.com/office/word" w:val="12" />
...
</w:compat>
When all three of the options are presented line spacing became less.
OpenXml refs:
ExampleDocs.zip (25.8 KB)
In the attachment two document. The first one with mentioned above compatibility options, second - same document but without these options.