The answer is yes, Raymond d'Aguiliers was definitely biased, his Historia Francorum qui Ceperum Iherusalem, isn't impartial at all, it's full of depictions of "evil turks" and "divine aid" for the crasaders. Being a Christian in the Middle Ages sort of explains his bias towards Christianity, however, it is also believed that he wrote the chronicle to rise up his liege Raymond IV of Tolouse.
