In some circumstances you should maintain a printed load sheet to satisfy the law
Loadsheet is required for heavy and RPT. Refer CAO 20.16.1. Otherwise you just need to check that you are OK. Mind you, a paper record is easier to defend at the Inquiry ..
One other concern when transferring data from the AFM to your own system relates to the datum used.
For instance, if the AFM calls up a trimsheet for the balance calculations of the loading system, it is quite common for the trimsheet datum to be different from the standard AFM datum. It is also quite common that the trim datum used is not specified explicity. As an aside, we do this to maximise the physical accuracy of the trimsheet calculation. One common trim datum used for lighties is the aft most limit of the CG envelope. This was pioneered in Oz by a Melbourne-based WCO in the 70s and 80s and a lot of the trimsheets floating around are plagiarised versions of that fellow's originals.
For interest, the general equation for the trimsheet entry argument IU is
IU = C1 + (W * (CG - TD))/C2
C1 gets rid of negative IU values in the entry start IU line. Negative numbers are so untidy.
W is the empty (or whatever) weight relating to CG
CG is the empty (or whatever) CG referenced to the OEM FS diagram
TD is the chosen trim datum referenced to the OEM FS diagram
CG-TD is the revised arm to the new trim datum
C2 is the chosen moment to IU constant, typically a power of ten
All very straight forward so long as you know what you are doing and take care with the housekeeping.
If the WCO has been sensible, he will have made sure that his non-standard datum is obviously not the standard animal. However, some folks don't worry too much about this and I certainly have seen some trimsheets set up to make the user fail should they try and lift the entry data without doing the appropriate due diligence checks and balances ... traps are there for the unwary.
Years ago, a mate who ran a maintenance shop and had a WCO, did some work on one of his cabin class twins, thought he should revise the weight data and, for good measure, reissued the call up for the trimsheet. You guessed it, he should have known better, got caught out and called up the wrong entry IU. The following day his Chief Pilot caught up to me with a plaintive "This doesn't work ..." My TDs were always set up for that to happen so that everyone had a bit of protection ...