Ok, that’s really good insight, so it boils down to France not respecting the 1935 treaty by refusing to declare Czechoslovakia as a victim of aggression?

No. So, there are two parts here: Romania allowing Soviet troops to pass through it and French and Soviet aid to Czechoslovakia.

I can't find the part I was thinking about when I wrote "so the Soviet Union never came to help Czechoslovakia under the Pact", and just I realized that there are actually two pacts.

The treaty mentioned is either the Franco-Soviet Treaty of Mutual Assistance or the Czechoslovak-Soviet Treaty of Mutual Assistance. Had France decided to fight for Czechoslovakia, the Soviet Union would also have. But the French didn't, and Czechoslovakia didn't fight (and therefore didn't call upon the Soviets to come to their aid), and so the Soviets didn't.

In the case that fighting had broken out, Romania would allow Soviet troops to pass through their borders, if the League of Nations declared Czechoslovakia to be a "victim of aggression" (not France).

I assume they’re talking of how the Soviet Union was the only country to sell weapons to Republican Spain in their fight against fascism, even as the Nazis and Italian Fascists were militarily and economically helping the reactionaries in Spain, and how France and England didn’t do anything under the guise of “non-interventionism”.

Yes.