Does training increase the player star level, or training facilities need to be upgraded, can someone explain how training facilities improve players abilities, am seeing the maximum abilities of players are 56 not beyond that even on D1 can I get more clarification on that, does experience of players also increased its values of the players? Thanks.

as I observe, there is no big difference that when training the players slowly improve, but when there are matches they are still bad, they lose when I bet, I noticed that it is impossible to play with computer modified teams because they are deliberately better and with the intention that you lose, regardless of whether you are active and  you are upgrading the team and the stadium......

training does not increase star level (potential), only player skills.

experience does not increase player value

-1 not good....

I believe a players star level represents how much experience they gain during training. A 1-star player will always be a 1-star player. Coaches, training faciity are a few things that help increase training % earned each day.