So how does reputation increase actually work?

Just finished my seventh season with Giana Erminio in Italy, my 4th in Serie A and I finally managed to win the title in a close contest with AC Milan.

I thought my reputation (which is currently at the edge of national, almost continental) would increase a lot, given that when I got promoted to Serie B I got a huge jump. Given that I also finished in the quarter finals of UCL, I was very surprised when I saw that my reputation stayed basically intact with just a “small reputation boost”.

Now how the hell does that actually work? Do I need to win titles? Do I need to win an european title to increase to continental reputation? How am I supposed to do that if now I just qualify for the UCL which is basically impossible to win with my current players?