Yep. Chuev conducted a series of lengthy interviews with Molotov over the period of 1969 - 1986 and he kept extensive notes about what Molotov attested to.
While I can’t seem to find an English language translation of 140 Conversations with Molotov, his other work, Molotov Remembers, is frequently cited as a primary source by historians.
Given that it’s testimony from something which was said many years prior to the interview I’d hazard a guess that Molotov was paraphrasing because the chances of it being an exact quote are vanishingly slim but such is the nature of historical work; often the eyewitness testimony is going to be somewhat hazy, especially long after the fact.
I personally would feel comfortable in saying that Stalin had actually said something to this effect, if not exactly word for word, to Molotov.
The past tense is in reference to the historical event, it doesn’t refer to the present state of Finland’s economy.
If someone had a post titled: “How Trump caused a rift within liberalism in the US” the past tense would not imply that Trump no longer exists or that he is no longer a politician, it would simply be referring to the political rift as a historical event.