Will I be sinful if the company engages in matters that violate Sharia without my knowledge, given that I invested in it based on a Sharia-compliant agreement?

The transaction mentioned is a Mudarabah (partnership). Among the conditions for its permissibility are: specifying the profit as a common percentage, not from the capital, and not holding the agent liable for loss. If any condition is violated, the Mudarabah becomes invalid, and the capital owner receives all the profit, while the agent receives a wage commensurate with their work (Ujrat al-Mithl).

There is no sin upon you if the company engages in some prohibited activities without your knowledge, after you have stipulated to it that it should only operate in accordance with Islamic law. However, if you become aware of this, you must prohibit it and withdraw your funds if it does not cease. You must also purify the portion of profit corresponding to its prohibited transactions by spending it on charitable causes with the intention of disposing of unlawful gains.