What happens if I pocket a C/m but accidentally touch a C/m on the table?
It will be a Foul. You will lose your turn, the pocketed piece will be returned, and a penalty piece will be returned. Presumably your touch caused the piece to move. According to the ICF rules:


The C/m and/or Queen shall not be moved or disturbed after the Break, except by way of a stroke. If touched, moved or disturbed the same shall be replaced in the original position by the Umpire, as far as possible and a Foul shall be declared against the offending player as per the Laws.

a) If a player pockets his own C/m by an improper stroke, the C/m so pocketed with a Penalty C/m shall be taken out for placing by the opponent and the player shall lose his turn.