Hello, thank you for your answer, I am currently using a couple Singletons for my Managers mainly because I assume you wouldn't ever want two game managers to be present at the same time and for ease of use, I find it nicer to use GameManager.Instance then to find it within Unity. But again using the method you suggested, and since all the objects in the original projects were made child of the game manager, they already have a reference to the game manager without it being public...
In retrospective using a system similar to the one that in the original project communicates between the SceneManager and the Game might have been better and, if I manage to finish tweaking the final things before the submission, I might try change it to be more similar to that even though that could mean creating a lot of events for a lot of possible situations which isn't probably the best ether.
But for now it's probably better to focus on making sure the game doesn't break and is at least a bit fun to play.
Thanks again,
Gual