The phrase tryadhvavyavastithāḥ sarvabuddhāḥ is unambiguously a Chinese idiom translated into Sanskrit in ignorance of Sanskrit Prajnāpāramitā conventions. This proves that the Heart Sutra was composed in Chinese.

Well, it proves that this Sanskrit version was a translation from the Chinese. Establishing that the Chinese Heart Sūtra didn’t have a different Sanskrit original is a different matter.