In addition to talking to the lawyer (and even getting a second legal opinion), I’d also talk to your Realtor and your home inspector. Even though they’re unlikely to be able to do anything, you might even want to call the title insurance company just to ask if they can be involved at all.

Where did you find the inspector who handled the termite inspection?

I don’t have firsthand knowledge of this, but I imagine if you were able to find a pest treatment company that had a history of coming out, that might count as proof for the lawyer. What did the lawyer you talked to say they could use to prove that there was an attempt to cover it up?