Will I be sinful for working as a financial manager in a government company that takes an interest-based loan, and will employees' salaries be unlawful if they are mixed with the revenues of projects executed with this loan?

It is not permissible to write anything related to a usurious loan, because it is a sin and its earnings are unlawful. One must leave the job if it is not possible to refrain from writing such a document, unless the person is compelled to stay in it due to the lack of any other livelihood for himself and his dependents. However, the salaries of employees derived from revenues mixed with usurious loans are permissible, because the loan enters into the borrower's possession after he receives it.