interrupt have precedence over barrier, if there is anything to interrupt (which is why if you have an interrupt on team, the game waits until your second move before attempting to cast barrier, as opposed to ASAP otherwise)
As for the suggestion itself, I consider auto battle to be something entirely different from manual battle. The expectation of your PvP lineup should work perfectly in auto is ridiculous. Part of the game is playing within known and reasonable rules to the best of your ability, not asking for the rules to change.
It is true that Auto AI is flawed, however, it is also deterministic. So anticipating AI behavior and building a team that works with it is interesting and challenging. Gomoku and Go are both played on the same board using same pieces, but they are different games. Don't go into a Gomoku game and demand it follow Go rules.