I already hit and broke the soft-level cap.
Museums just broke it.
I do suggest 1 thing.
Make sure you get level 9 museums with everything else at soft level cap (i think my towns are only 21 though). At level 21 I was at 79 happiness. 80 = a wine level. So I was forced to upgrade a building (i chose museum for the long term). Doing it on all 4 of my towns cut wine by 12 per hour.
I just need to break the soft cap on Tavern + get more treaties so Im not losing 3 wine per hour and I can start to profit