Fundamentally, to what extent is a Limited Partner subject to a
potentially ruinous financial situation resulting from financial
wrong-doing committed by the Managing Partner?
Civil tax liability
Under U.S. tax law, a limited partner in a limited partnership that is taxed under Subchapter K of the Internal Revenue Code (i.e. as a partner) is responsible for that limited partner's share of all taxable income of the partnership, for all interest owed on the unpaid taxes, and generally speaking (subject to very narrow exceptions), to penalties assessed on the unpaid tax. Moreover, frequently, the limited partner has no right to be involved in the tax litigation by the tax matters partner of the partnership on the issues that matter.
The limited partner's tax liabilities to the federal government and any other taxing authorities with a pass through income tax system are not limited to the limited partner's investment in the limited partnership.
Criminal liability exposure
The limited partner will generally not have any criminal liability for tax crimes committed by a general partner or other partnership official engaged in tax work on behalf of the limited partnership without more affirmative involvement in and endorsement of the misconduct, although the partnership itself might See U.S. v. Arthur Anderson, LLP (which was reversed on appeal by the U.S. Supreme Court because proof of intent was inadequate, but demonstrated the principle.)
A limited partner would bear the limited partner's pro rata share of a criminal fine but that would be limited to the limited partner's investment in the limited liability partnership.
Mitigating the harm with a lawsuit
The limited partner will usually have a right to bring a civil action (i.e. a lawsuit) against a general partner whose management of the taxes of the partnership cause the limited partner to incur tax penalties, on a breach of fiduciary duty theory, but the limited partner will generally not be able to recover back taxes owed, or interest on back taxes owed, in a lawsuit of this kind.
The limited partner might also be able to bring a lawsuit on other theories that might involve an award of punitive damages against the general partner or other person handling the taxes of the partnership who was involved.
The legal theories are complex and many would involve a "derivative action" rather than a direct suit against the general partner or manager.
The "what to do about this situation" part of this question is beyond the scope of Law.SE as it calls for individualized legal advice.
A good response to this situation would be challenging to formulate for even a specialist business law and litigation practitioner with far more factual detail available. Litigating of issues like this routinely costs each side hundreds of thousands of dollars and can take multiple years.