Under the expectant gazes of everyone, Rhein shook his head with regret: "Basically, for every question I asked, I couldn't hear a clear inner response."
This is actually normal. After all, Rhein is not a Prophet Wizard; even if he understands some basics, it's just a small skill. If he could truly replace a Prophet Wizard, that would be abnormal.
Rhein continued: "However, there is one question that received a definitive answer."
"It is certain that this relic is undoubtedly safe. This is the only firm inner response I received from the Silent Deity."
Although this answer doesn't help in finding the hidden room, it at least alleviated a previously unmentioned concern they've had—
Since the suspected first owner came back through some passage, did he leave? Could he still be staying in the hidden room?