With regard to wearing leather shoes on y”k and t”bav, if the sole is not leather but the top is , is this still a problem? Thank you. All the best.
The problem applies to leather shoes irrespective of the sole. Thus, it is forbidden to wear leather shoes even if the sole is rubber.
This is clear from the rulings of the Shulchan Aruch (Orach Chaim 614) and later authorities.