Thanks a lot for the details, it raises one larger question for which im not positive and that may induce a lot of approximations in my resoning :
When we resolve the stack, we resolve the last thing that was put on it, but then do we get to play other thing before the 2nd last thing resolves ? Or do we just sit and wait until the stack resolves unless there is a trigger ability that triggers and allows us to play things again ?
In order for something to resolve all players must pass without adding anything additional to the stack.
"405.5. When all players pass in succession, the top (last-added) spell or ability on the stack resolves. If the stack is empty when all players pass, the current step or phase ends and the next begins."
"608.1. Each time all players pass in succession, the spell or ability on top of the stack resolves."
"117.4. If all players pass in succession (that is, if all players pass without taking any actions in between passing), the spell or ability on top of the stack resolves or, if the stack is empty, the phase or step ends."
So, if for example, Player 1 casts
Wrath of God and passes priority, you (Player 2) pass because while you don't want it to go off but are pretty sure Player 3 will counter it because they have the mana open to do so and would be even worse off than you, Player 3 does exactly what you expect and casts
Counterspell, Player 4 is fine with this and passes, Player 1 responds to the
Counterspell with
Dovin's Veto, Players 2-4 all pass and it resolves countering
Counterspell and now
Wrath of God is up for resolution again, but these things must be decided on again because it still hasn't had everyone pass in succession, so now that Player 3 has failed to stop the Wrath you could toss out a
Tibalt's Trickery in response to the Wrath despite passing the last time it was at the top of the stack waiting to resolve.
Since CtC needs to be resolved first, if you can it means you can play something first then cast CtC on the same stack no ? Because it feels to me that it is the same mechanism you described when you talked about suspension triggers and stack.
Casting anything before CtC will not allow it to be copied by CtC, as it has already been cast. The only reason it works with this double
suspend scenario is that other spell doesn't actually get cast until after CtC.