The seller's agent does not represent your best interests and that is why it is always best to always work through your own agent. Continue to try to work thru him or her and if you aren't satisfied with the results, suggest that you contact the seller's agent and see how your agent responds to that.
If you are still unsatisfied, I would suggest that you speak directly to your agent's Broker to get the help you need before going to the seller's agent.
I would suggest contacting your agent and inquiring what they have done to see this aspect through, and find out who they have contacted. Your agent telling you, "doesn't want to ask the sellers agent if any of this has been done" is a warning sign! So make the calls to your agent, they are getting a commission from their work so make sure they are actively representing you!
If your agent doesn't provide the answers, then YES, contact the Listing Agent of the home you're buying to inquire about the engineer's foundation report
If you feel that your Buyer's Agent isn't fully representing you, then you have the right to terminate them, but there may be some issues so contact a Real Estate Attorney after reading any Buyer's Contract you may have signed.
Here's a good article: http://www.realtor.com/blogs/2012/04/03/can-i-fire-my-realto
That said I doubt very much that your agent contacted the sellers, as this would be entirely inappropriate, they should have contacted the Sellers agent. I would suggest telling your agent that you want them to email the listing agent and blind copy you so that you can see that this was done and in the email politely but firmly demand a response in an effort to keep the transaction on track.
I also think you need to keep in mind that at this time of year it's not uncommon that people are tied up with holiday /family things and may not be immediately available to respond. However it's more than reasonable to expect your agent to get this done for you today and to receive a response no later than Wednesday. If you haven't received a response by then I would ask to speak to your agents' Broker in Charge and discuss things with them.
Good luck and I hope you have a Merry Christmas.
I don't see any reason why your agent would impede the process. There could be multitude of reasons. Communication with your realtor directly is the most appropriate course of action.
Best of Luck