I'm of the opinion to always allow a certain amount of creative freedom, but there are some fundamental things that can't miss. I know that 2d/3d artists in Taleworlds have some autonomy but it's only the art director's duty to have everything tied up at the end of the day.
Regarding this issue of chainmail we can see this lack of monitoring; each artist has decided what and how with basic guidelines that are too carefree. That's why we see all these colour inconsistencies in different pieces of armour.
A retexturing where the colour of the chainmail is a transversal and homogeneous variable across all models is entirely possible (in two weeks at most this would be done in a professional environment - plausible). However, I doubt Taleworlds would want to spend time on this.