When they told you that they'd still be interested in viewing the report... it probably meant that if the report came back showing that the foundation issues that were raised weren't a big deal, and could be easily repaired at minimal cost, they might consider coming back into the deal.
Apparently the report showed enough of a foundation issue, that corroborated their reason for terminating the contract, and they don't feel it necessary to give any additional feedback. While I agree with you that it would have been nice to just say "thanks... but we're still out of the deal"... it just didn't happen.
There's certainly nothing wrong in having your Realtor reach out to them, and just ask as to their status... but in reality, I think we already know the answer... don't we?
Their silence is not being dis-respectful - they have already pulled themselve out of the deal. In fact, the Buyer is being very considerate and reasonable by making sure they haven't over reacted; not having all the pertinent information.
Apparently, the report did not minimize their fears. Now, it is time for you and your agent to move on and market the property according with the newly discovered information.
You're not in the dark...you're simply hoping for a miracle. Forget what has happened and look forward to what can happen.
Put the house back on the market and find a new buyer. If the report reflects badly on the property, you'll need to disclose this to subsequent buyers. Consider if you can resolve the issue and have a positive report to offset the negative or if you need to drop your price to attract a new buyer willing to take the problem themselves.
It's possible if they see the house back on the market at a reduced price they may come back before someone else does. In an ideal scenario they will come back just as another offer comes in.
2. If they terminated the contract, it means they are no longer interested in the home at the price and terms originally contracted under.
3. Honestly, it sounds like your frustrated, but also a bit desperate as your trying to push a rope, in other words, you're trying to convince a buyer who terminated the contract to jump back in the deal. I don't know what you think your agent should do at this point...the deal is dead and trying to resuscitate it will likely only lead to further frustration and there's no reason for your agent to be trying to raise the dead.
4. Let it go, get your house back on the market after the foundation issues are taken care of or adjust your price so that another buyer will assume the risk.
My bigger concern for you is that if you've asked your Realtor to contact them for feedback, and your Realtor hasn't done so, you need a different Realtor. But again, believing the best, perhaps your Realtor has made the request with no results. There's only so much a Realtor can do.
Going forward, you have two choices - price the property to sell with a damaged foundation, or repair it and price accordingly. The concerns buyers have about repairing the foundation themselves isn't so much the foundation as the collateral damage that can result - broken plumbing lines, cracked sheetrock, windows, doors, etc. They will WAY over-estimate the cost of the repairs if they have to accept that liability in the purchase; you would be money ahead to make the foundation repair yourself.
Hoping you have a new buyer soon and this will all be behind you!