We have a critical job and we want to ensure correct balancing before we proceed further. we do not know calibration or any complex theory. What do we do?

In this given situation, user should realize all digital electronics works between +/- 5 V. It is an interpretation of the results that matter. A simple method is to balance to half the accepted values.
Say for a tolerance of 50 mmg you balance the component to a residual unbalance of 25 mmg as indicated by the machine.
Now without disturbing the mounting, drive, you change the reference position. This can be done by indexing the universal shaft by 180(Any given angle) degree in end driven machines or by shifting the reference sticker by 180(Any given angle) degree in belt driven machines. Now measure the residual unbalance amount of the component. If, the residual unbalance indicated is within 10% of the first value, you can be sure that all the errors like drive errors, drift in the electronics etc have been accounted and the component is well within the residual unbalance permitted.