I think we need to look for the very first original source of the text to see what year is mentioned in there. The books I used were from the 19th century. This is well after Joseph Justus Scaliger re-adjusted the time scale.Hopefully an innocent question here.
Why on the one hand we can think that Jesus was born in the 12th century.. Yet, these 4th/1st crusade accounts literally say "in the twelve hundred and two years since the incarnation of Christ"
Additionally, with Jesus living in the 12th century it makes sense to look for stuff related to his life immediately after his death, i.e. 50-75 years later in the beginning of the 13th century. It makes way less sense to look for things 1,200 years later. We can not even figure out what flags the United States had in the 19th century well within the age of photography.
Just my 2 cents there, but yup. We need to see what the original source of the text is. Somehow, I doubt it exists though.