The normal pile positional tolerances in the UK are 75 mm on plan and 1 in 75 on verticality for vertical piles.
If the piles are installed as single piles or only in pairs, they will be effectively free headed in at least one direction and the pile reinforcement should take account of positional tolerances.
Once a normal three pile pile cap or greater is adopted, thge piles are effectively restrained in two direction. Under these circumstances the pile cap iteself will take out the positional moments in bending, leaving the pile tom cater for vertical load only. Thie means less reinforcement in the pile and is why most piling contractors will qualify that they expect the pile cap and/or ground beams to take out the position tolerance moments.
If a pile has been built out of position, the pile cap or ground beam will need to be adjusted to take the pile back into the sub-structure. This will involve additional ground beam/pile cap concrete and possibly reinforcement. Unless the pile is significantly out of position, it is unlikley that major re-design of the sub-structure will be necessary.