Congrats.
It is indeed very RNG dependent. I had (what I thought) a very overpowered team. T5 & T6, did it on auto. I had to remod for T7, I knew the mods were poor, speeds were my barrier. After re-modding, 5 tries resulted in me getting nowhere. They targeted my elder and wiped him out every time, so I just restarted. Try #6, they went another way, and I could easily take them down. Nothing to do with my strategy, it was just the right opening move was needed by the game to succeed.