My apologies. It’s not training. It’s challenges & tutorials. When you select challenges & tutorials, the choose a challenge screen shows how many stars you have gained for each challenge (in orange or red.) Gray stars show tutorials that you have not received any stars for. Locks show locked challenges. When you are in a tutorial or challenge you can get up to three stars. Once in a tutorial or challenge, the number of stars you get is related to your final score. The chart showing the number of points needed is at the top on the right above your name. Once you get stars for a specific tutorial you only get additional stars if you exceed the number of stars you already have. For example if you gained two stars on specific challenge the first time, if you play that same challenge again you will not get additional stars unless you get the score that corresponds to three stars, at which time you will gain one additional star and the two stars that showed on the choose a challenge screen will change from two to three. I hope this helps and doesn't make it even more confusing.
