None of the coins are hidden in the Celtic temple but you may have missed some in the lower caverns where there are 41 coins. Think of them as four levels with each level guarded by a different coloured blob. Think of the 'doors to enter the caverns' as top from left to right as doors A - D and the bottom as doors E - H. In the caverns 1 - 4 indicates the doors in each room to use.
Level 1 (red blob) Enter Door B: 1 (1 coin), 1, 3 (5 coins & out), 2, 1, 2, 2 (5 coins & out), 1 (5 coins & out), 3 (1 coin), 1, 2, brings you back out at B.
Level 2 (blue blob)Enter Door E: 2 (1 coin), 2, 2 (5 coins & out), 4, 3, 3 (5 coins & out), 2, 2 brings you back out at H.
Level 3 (green blob) Enter Door D: 1, 4 (5 coins & out), 3, 1, 1 (5 coins & out), 2, 1, 1, 2 (1 coin), 2, 1, 3 brings you back out at C.
Level 4 (yellow blob) Enter door F; 4 (1 coin), 2, 4, 2 (1 coin), 2, 3, 3 brings you back out at F.