Does one causing harm to their brothers at work, unintentionally, count as an injustice that necessitates restitution, given their unawareness of the perpetrator?

As long as what happened to your brothers was unintentional and without any intent to harm, and did not cause them financial loss, then there is nothing upon you. This is because Allah the Almighty has pardoned errors, and you should not inform them of it, lest it cause hatred and estrangement. The Messenger of Allah, peace and blessings be upon him, said: "Indeed, Allah has pardoned for my nation their mistakes, their forgetfulness, and what they are coerced into."