Is there any chance of having the arcade machine high scores saved and kept when reloading the plugin?

This can be done by enabling entities to persist when the plugin is unloaded, in the config. This will allow arcade scores to be persisted throughout the wipe, since the same arcade machine entity will last the entire wipe.

Note: Arcade scores can't be persisted across wipes as the plugin doesn't currently support cross-wipe persistence for entity state. Meaning, the entities will be respawned at next wipe, but things done to/with the entities will be forgotten.

If you are looking for something different than what is offered today, such as cross-wipe persistence of scores, or global scores synced between arcade machines (if you placed multiple), then we could discuss those as feature requests.