I can attest to having a similar issue in a startup that got large, we used one of the big firms for 100% of the work and should have been doing 10% of it with a specialized firm. It's not really startup advice you get, but it can be very costly later. Glad you got it sorted out.

For what it’s worth, $75k and whatever time you spend on this doesn’t seem like a massive amount. I feel like you took a risk when you had many other things to do and the risk was calculated and overall worth it — even if you got unlucky.

Is it possible to get the fine covered by malpractice?