Isn't FindAllPagesWithCriteria or FindPagesWithCriteria suppose to work on properties inside a Page block or a Global block?
var repository = ServiceLocator.Current.GetInstance();
PropertyCriteriaCollection criterias = new PropertyCriteriaCollection();
Condition = CompareCondition.Equal,
Required = false,
Name = "Heading",
Type = PropertyDataType.String,
Value = "My heading"
PageDataCollection result = repository.FindAllPagesWithCriteria(ContentReference.StartPage, criterias,"sv",new LanguageSelector("sv"));
I don't think that's possible. You could however search for a specific block in a content area, but I'm not sure if that's something you need.
Check this blog: http://talk.alfnilsson.se/2013/06/05/find-pages-containing-a-certain-content-in-a-contentarea/