You don't specify your state; but, in general, only the IRS and the state income tax
agency deal with non-profit corporation violations. It appears that the 501(c)(4) regulations don't require that the corporate charter restrict the activies to allowed activities, as the 501(c)(3) regulations do. This is conjecture on my part, but my speculation is that, as, for the most part, only the organization and its members are effected by the loss of tax-exempt status, it's up to the members to monitor the activies of the association. As noted in the IRS documents you've commented on, contributions to 501(c)(4) organizations are rarely tax-deductible.
If there were a question of the corporation violating its charter, then there are pontentially agencies in the (state) Secretary of State's office that would deal with it, but it's not clear you have that remedy here.
This is PURE speculation on my part, but bringing the matter up at an association board meeting and/or a pontential misfeasance lawsuit against the board (for allowing the organization to lose its tax-exempt status) seem the only possibilities.
If you hear otherwise, please contact me through allowed channels here on Just Answer. I'd like to know if there are other options, in case the association board for MY HOA screws up.