Speaking as someone on the flip side of the situation, generally: as stated elsewhere, it is relatively unlikely that the architect is completely unaware of what can be accomplished with the tools, even given a particular time frame. Much more likely is that there is a communication breakdown. This can be true even if their intent is to "challenge" you: they should have better communicated that that was, in fact, their intent.
What I think a number of the existing answers have missed, however, is this: if this is the person who is primarily responsible for assigning the work that you are doing, on a technical level, your first step (whether you're an intern, a junior developer, a senior developer, or even an architect who has to report to a more-senior architect) is to go to them and simply say "I think that I may not be understanding the request accurately, or missing something else about it, because I'm not seeing any path forward on this that can be successful given the current constraints (of time, technical skill, or whatever else)."
Apart from trying to be very up-front about it to prevent stress or negative situations, I would absolutely up the stakes for an intern who had done something solidly, after praising them and making it clear that they had succeeded at the task I initially set them. Because the initial task would have been relatively low-hanging fruit specifically so that I could be confident that they would have a pretty good chance of succeeding. To give them the best benefit from their internship, I would then give them additional work (read: responsibility) gradually, until it reached the limit they could handle or we ran out of time.
Unfortunately, not managing to "telegraph" this to someone is a really easy and really common mistake for folks to make, especially if they aren't used to needing to monitor such a situation carefully — they may actually expect you to "push back" on it and ask for guidance, especially if they haven't mentored many very-junior folks before and most of their previous mentees were already at a level where they felt comfortable saying "wait, how the heck am I supposed to do that?"
Nothing about this has to be confrontational, mind you — it is, or should be, absolutely expected that an intern should be asking for guidance on something where they don't understand how to accomplish what is being asked of them. If they're really that senior, it may be that they have knowledge of a pattern or "trick" that you aren't yet aware of that makes it more possible than it currently appears. Or it may be that they're trying to see if you are in fact capable of realizing when there is a problem (and, in my opinion, doing a poor job of approaching how to test that). Or possibly some other explanation.
But in every plausible explanation I can think of, even one ones where this is a "bad" company, your best "next move" is to talk to the person asking you to accomplish this about the approach they think you should be taking and what their expectations of the result are. If that doesn't produce anything helpful, your manager is the next stop, to ask for help in resolving the situation.
