From what you posted about mod leveling.
Mod Levels
EA_Jesse writes:
“Mods can reach up to level 15
Each level up increases the primary stat on the Mod
At levels 3, 6, 9, and 12, a secondary stat will be added or an existing secondary stat will be increased
Mods are upgraded by spending credits to increase the XP of the Mod.
It is possible to receive a large XP boost immediately upgrading the Mod's level.”
So after reaching level 12 secondary stats are done. They only change or add at level 3,6,9, and 12.
Definitely some good info but definitely needs some corrections.