Only just seen this. I don't feel like double "promises" more as some have suggested. Pass to me is correct because:
a) The majors are the wrong way round. We will never win with ♥ vs ♠
b) The vulnerability makes any sacrifice poor especially without shortage
Definitely prefer 4♦-2♣ to go into 1♣. On the border re 5♦-2♣.
I like splitting the NT ranges and understand your arguments for TriBal. However, I also like the unbalanced diamond (5552 structure) rather than a nebulous 1♦. Play Mod Mexican 2♣ with ...
South has definitely kept the ball in play and North could have done a lot more:
1♣ is good,
2♣ is borderline,
3♦ is poor (a 3♥ SPL jumps out at me as automatic)
Pass is just making a bad situation worse
I answered NF, NF in all 3. I understand that 2♦ might be passed and therefore some people think that these bids are F1/FG. However, this is quite an easy auction to set up a force (3♣) and 2♦ in itself is a hugely descriptive, yet ...