1. The API documentation is very detailed. An average plugin developer would have no trouble understanding it. you are just dumb if you don't understand it.
https://nighterdevelopment.github.io/smartspawner-docs/developer-api
2. The egg-changing action for spawners is only meant for administrators. Normal players can never obtain mob spawn eggs, and they also won’t have permission to use spawn eggs on spawners (you can check the plugin permissions).
3. The hologram you can easily remove it by running the command: kill @e[type=minecraft:text_display]