Allow me a small opinion.
It is true that a history researcher can not have a clear view of the way batlles faught by each individual in them.
Each warrior faught the way he felt that would help him to survive 1st and then win the batlle.
A game's engine such the M2TW have some limitations.
For example we can not have diferent style warriors in the same unit. We hope that will change in the future games.
Now...for norman knights.
We must not forget who Normans were.
Vikings that settled in french teritory and adopted some new warfare tactics from the rest of the europeans.
In the Frankish empire that influenced the west and central europe with warfare tacticks and equipment,the heavy cavalry was not the same style of the Lombard,Arabic,Armenian and last the Roman ones.
Frankish heavy cavalry used short spears (same as their infantry) to make their 1st impact. The walls of shields ans spearheads the enemy infantry presented against the cavalry frighened the horses that often refused to advance! The most comon tactic those cavalry man had in their disposal was to go near the infantry lines throw their spears and distract the infantry lines to the moment they (the horsemen)could repeat their attack, with their swords this time.
That tactic was efective to central and west europe that bowmen were rare and infantry also used 2-2.5 m spears.
Normans forced to change their tactic and adopt the charge style we all know today when they arrived (as raiders 1st)in Itally!!!
There (in Italy)had to deal with old fashion armored but armed with long lances Lombards, with the heavily armored Saracen horsemen and later when they came across with Tagmatic horsemen of the Romans that arrived in Italy as reinforcements.
The "khight" style we know today as Norman is actualy a Lombard one that was a version of earlier Roman influences...
How do we know that.
In the Italian Roman(byzantine) campaigns descriptions Romans faced the Normans as Lombard allied forces...They were clear about how those "normans faught".They discribed that they launced their short spears (in M2TW we can only show it as javelin)and returne dto repeat their advance.
TO the Roman generals was adviced to keep tight infantry formations with more heavily armored(that the average) infantry men and counter attack them(the normans)with light range cavalry that their arrows could easily penetrate their chain mails!
Normans after the settle in Italy adopted the longer lances (shorter than Roman ones though)and added scale and lamellar cuirasses of Arabic and Byzantine style to their chain mails.Also they adopted the Lombard tight cavalry charge and added arabic bowmen to their armies.
The Norman warfare lessons spread in all central and west europe mainly after the 1st crusade.
So if a mod should acuratly wants to show to its fans the evolution of the Norman or norman style cavalry it has to show them as javelin men at early era and as lancers at the late era...
I hope i helped.