There's nothing to even suggest that Queen is considerably stronger than Jack. The name and relationship with the others can easily be based on his age, but he's explicitly referred to as a right hand man and has proven it. His bounty is very close despite his younger age also... the only reason they might stay above him in a dog eat dog crew is due to a lack of certainty in beating them.
That was just a bad translation, Jack is obviously the furthest thing from a Right Hand Man among the All Stars.
His bounty is more than 300 million lower than Queens. There's a more significant bounty difference between Queen and Jack than there is between Smoothie and Perospero who is not even a Sweet Commander.
The bounty difference between Queen and Jack is almost Five Times higher than the difference between Smoothie and Cracker.
King and Queen are at every step separated from Jack.
Jack is literally used as a hype tool for their introduction.
King and Queen are separated from Jack and made to guard the execution platform.
King and Queen are separated from Jack and made to guard the routes to the top.
King and Queen receive hype from Zoro who perceives them as difficult opponents to even attempt to run around on the way to the roof.
Maybe Jack has more room to grow, but if we're talking about the present he is presented as their inferior by no small margin.