Well, I think I'll put my nickle's worth in....
I tend to lean toward the Warrior as Journal Writer, and here's why:
It would just seem to make sense that an organized army such as the legion would have a historian. Indeed, if we look back at our own history, there were some wars where a minor soldier was given the task of keeping records of the unit's actions. This soldier was mostly a lower rank, mainly enlisted, but instead of writing great tales of the army's victories, it would tend to lean more toward his particular commander; which is usually the one who assigned him this job, if only to make himself look good.
Just a thought,
Zandervix