I believe the generally accepted interpretation of Scenario 1 is for the treatied alliance(s) to fight for the duration of the conflict - the treaty is still in effect during the cancellation period, meaning it is activated and all its effects applied regardless of the cancellation period expiring. So the obligation would kind of get extended until the conflict ends.
Keep in mind however, CN is much more a social than a political game. That and the fact we have no world authority or limitations (like the UN) means treaty interpretations will vary wildly, with moral condemnations and backroom deals developing beyond the text. Though some things are more or less frowned upon universally at least on the surface (bandwagoning, spying, etc), those are purely moral sanctions.
Intelligence clauses like in Scenario 2 would likely fall too deep into that subjectivity and vary too much from alliance to alliance for a definite answer that emcompasses generally accepted customs. But really I don't know, I've never been high gov, just a regular grunt.
Keep in mind these are amateur impressions like yours, people who are actually in high gov and make this game actually work would answer more precisely.