What is the ruling on the work of an engineer specialized in filling out forms and procedures for disbursing entitlements to injured workers from social insurance, knowing that these insurances invest their money in usurious banks?

As long as your work is limited to filling out forms for injured individuals to claim compensation for damages incurred and completing the procedures that enable them to obtain their legitimate rights, there is no harm upon you in that work or in benefiting from the wages you receive for it. This is because an injured worker, in some cases, has the right to be compensated for their injury and to have it recorded so they can fully receive their right.