King Richard was known as "Richard the Lion Heart", not Richard the Lion Hearted. A common mistake among people who don't research history.
The Knights Templar were attacked and essentially destroyed in the early 1300's (James Molay, the last master was burned alive in 1314), so the series has to be set around that time. We clearly hear a Knight holler F*ck in frustration. F*ck did not come into use until 150 years or more later, so no one living in the 1300's would be hollering it.