The server error showed some interesting coding features of 3 CG reward FSDs:
1. They have their own item ID and declearation codes in server data base.
2. In their declearation codes there is no user customize exp effect attributive(var), instead it's hardcoded value(int), not subjected to change.
3. In client side. Exp effect mod availability check could be just tied to item type not item ID. So for all these items having their normal versions that can be applied effects, these CG items are not able to be intercepted by "no exp effect available to this module". This made us able to press adding effect icon in game.
4. Then when we apply exp effect on a CG reward item, client throws this item ID to server asking to put exp effect, server checked request but did not find a var to change effect. Instead it just find a hardcoded int value (this time there is no effect added on FSD, assume that value field could be a hardcoded 0). It cannot be changed and server returned an error.
I think the best way for both us and dev could be simply adding hard coded mass manager attributive to these CG items.
Some player want deep charge on size3 and 4 may feel unhappy but at least we still got fully moded module and dev minimized their bandwidth solving this.