Regarding the backhand play at shortstop, it seems like the error was unrelated to the backhand play.
What did you see?
If he had time to plant and make a good throw after fielding the routine hop and would have been expected to get the runner out but failed to do so because he dropped the ball, then it's an error. If, however, the reason he dropped the ball was related to the necessity of recovering and getting set after making more than an ordinary effort, then it is not an error.
I would discourage broad generalizations, such as the assertion that ANY backhand play requires more than ordinary effort, that prevent you from using your experience to make a subjective assessment of the actual play that unfolded before your eyes. Ask, "Should a shortstop of average ability for this classification of baseball have been expected to make that play?" If yes, charge an errror. If no, don't.