Generally the tile installers have two jobs 1 install the tile and 2 level the top of the bond beam. So the first question is did they level the top of the bond beam before they poured the coping? If they didn't it may not matter or it may matter a whole bunch. Because the one sure thing is the water is going to be level. So the first thing your tile guy is going to need to be sure of is that the tile is level. You can calk the joint between the tile and the coping with silcone caulk but the tile line MUST be level.