Issues with Experience Item Functionality and Stack Usage

1.

Could you add support for selling experience items directly in the shop?
After configuring them, they do not seem to function properly.

2.
When using the item, it is consumed multiple times at once.
My server uses a stack plugin:

https://codefling.com/plugins/loot-table-stacksize-gui

3.
For some specific event NPC drops, could they be configured like this directly?

"ShortName": "chocolate",
"Inclusion Chance Percentage": 80.0,
"Minimum Amount": 1,
"Maximum Amount": 1,
"CustomName": "novice's pamphlet",
"SkinID": 2863540162

When the item drops using this configuration, it cannot be used normally.

4.

The experience value is also incorrect and does not follow the configuration:

"Item list": {
"novice's pamphlet": {
"displayName": null,
"shortname": "chocolate",
"skinID": 2863540162,
"effects": [
{
"min": 2000.0,
"max": 2000.0,
"type": "XPInjection"
}
]

According to the configuration it should give 2000 XP, but after using it, the player receives 7000 XP instead.