You may be correct about the source of the rumor, but it’s also not that hard to go through the history and see which tests have already been recycled internationally and which haven’t. That might not narrow it down to a single test, but it will narrow it down to a manageable handful.
And even if you don’t illegally acquire unreleased exams, you can compile pretty good answer banks by reading old CC threads. It’s the test recycling that’s the problem, and unless ETS is willing to stop recycling tests, the problem will persist as it has for years, allowing unscrupulous cheaters to prosper. Oof I hate that.
You may also be right that the bottleneck for test making is qualified personnel. But that’s a very surmountable problem, so if that’s the bottleneck, ETS should be able to overcome it with little difficulty.