Indeed. The fact that no-one among the entire staff of the hospital over all those decades endeavored even to identify the patient's only language tells you that it was not a hospital.
It is really shocking that he never picked up Russian. I understand that Russian and Hungarian are almost as different as Japanese and Hungarian, but he should be able to learn the language just by hearing it.
Someone else recognized the language he was speaking, and that it wasn't actually gibberish (and so he wasn't some crazy old man).
Something even the USSR was pussyfooting around in its later stages…
For example https://en.m.wikipedia.org/wiki/Rosenhan_experiment
Displacing locals and moving Russians in, they claim the local population is ethnic Russians...
Getting away is not easy