Interesting.
I was thinking more of an existing contract for deliveries over time at a contracturally fixed price. Is the Chinese buyer, perhaps the government, still required to purchase at a tariffed price.
Which raises the question, can the Chinese government waive the tariff on purchases it makes ?
Likely the question of Chinese tariffs being applied to existing contracts would be up to the Chinese government, but my instinct would be that they would not, at least officially.
With China, Im not sure theres a way to really know what its doing internally.