All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
As for working in man-made courts as an accountant, if this is related to an administration whose provisions are limited to administrative and regulatory procedures and it does not deal with issuing judgment regarding the money, lives, and marriages of the people, then there is nothing wrong with it, Allah willing. However, it is better to leave this job if you can find another one.
However, working as an accountant in an administration that deals with the judiciary, such as the judges and the lawyers and so on, is not permissible because it is helping in this great evil, unless the worker is forced to do it, such as if he does not find another job to earn his living and spend on those whom he is obliged to spend on; then, in such case, he may continue to do this job while looking for a permissible job where he does not do something forbidden or helps in what is forbidden.
Allah knows best.