EDIT: Well, apparently it fixed by itself waiting a few days (more than one)

Greetings!
I have recently started playing MM9, about 15 years ago i played this game for the first time and I never completed it so I wanted to remedy this situation. I have reached the point where i had the war council in 2 weeks and then Sturmford and Drangheim went to war, I did the quest until I had to get the treaty from Kira the Cold the day after but then I realized I hadn't killed the dragon yet so I went to do that instead (15 years ago I had stopped playing right before going to the dragon so I felt the urge to complete that before continuing the main quest), i thought there'd be no harm in waiting a few days despite being asked to go back the day after...
Now i can't get the treaty (the quest even disappeared from my journal) nor i am able to continue the unite the clans quest

I tried looking on the internet and found nothing except a warning in a walkthrough saying that if you don't go get the treaty the day after you might not be able to complete the quest (If only i knew that ahead of time...)...is there any way to fix this? I'm not afraid of getting my hands dirty with an hex editor or something similar if needed, what i'm afraid of is losing all I have done up until now

Sadly, I don't have a save before killing the dragon