Common sense and good airmanship should always prevail with these things.
In our company when the loadsheet is received the captain checks the pertinent details, flight, dates, pax, DOW/DOI, registration etc etc. Then he enters the relevant bits and pieces into the MCDU like CG% and trim. He calls out the bits and pieces from the loadsheet, I check them against the loadsheet as well as writing them onto the performance sheet (we do ours manually). When it comes to trim we both double check the printed loadsheet to the trim wheel (ie: look down and usually point our pens
) and confirm verbally that the CG% marries up to what the loadsheet is saying in terms of the up or DN. That then gets entered into the MCDU along with the V speeds and flex setting that I give him and we cross check from the performance sheet. As an aside the PF would have set up the MCDU with the planned ZFW and ZFW CG% plus the expected total fuel on board, if refuelling and the actual is not yet known. As the skipper enters the ZFW details having the "planning" data already entered allows for a gross error check. Then the take off weight and landing weights can be checked along with taxi fuel and burn to the MCDU and the loadsheet as a further check.
By the way when I was undergoing my type rating I was always taught to set the trim wheel by rotating it to line up the CG% rather than the UP or DN bits and NEVER EVER to rotate it by referring to lower ECAM screen. Set the % and then check that it is UP or DN as required as a further check. It is so so easy to inadvertently set it UP rather than DN or vice versa if you don't set according to the %.
After engine start the checklist has a line for "pitch trim". I personally make a note of the pitch trim from the loadsheet on my scratch bit of paper clipped onto the sliding window. Again we verbalise what the pitch trim is and check this against the MCDU perf page, the trim wheel and finally on the lower ECAM screen. As a final gross error check we always make sure that the trim is in the green band which is the final gross error check if you like.