(In reply to Richard Newman [:rnewman] from comment #4)
> I think the code as written will grab intl.properties instead of actually reading
> the real value.
It will indeed, but that's not necessarily a problem if it sets the pref the same way (setComplexValue(..., nsISupportsString)), as long as that URI resolves to something that exists and contains a value for that pref in both Firefoxes. It's hard to think of cases where that wouldn't hold, but that probably explains why this isn't affecting most Sync users.
(In reply to Richard Newman [:rnewman] from comment #4)
> I think the code as written will grab intl.properties instead of actually reading
> the real value.
It will indeed, but that's not necessarily a problem if it sets the pref the same way (setComplexValu e(..., nsISupportsStri ng)), as long as that URI resolves to something that exists and contains a value for that pref in both Firefoxes. It's hard to think of cases where that wouldn't hold, but that probably explains why this isn't affecting most Sync users.