So, I was wondering about the time to get my first L8 elephant (citadel or royal, still deciding 3FP vs 2% attack).
I used 1000 attacks = 150 fragments. So if my guild finishes 1st, 2nd or 3rd, the fragment values are 78, 69, 62, respectively. I wouldn't consider the difference significant, I used 70 for calculations and it yields the following timeline
1000 attacks per season = 8 seasons (8 months - you would have close to a L1 extra)
2000 attacks per season = 4 seasons + (4 months plus- get it in 5th month)
3000 attacks per season = 3 seasons + (3 months plus - get it in 4th month)
4000 attacks per season = 2 seasons + ( 2 month plus - get it in 3rd month)
5000 attacks per season = 2 seasons ( 2 month)
more than 5000, can be calculated the factors are here.
So, the new building will take considerably longer than the SOH timeline. First, a 40% reduction in the amount gained by rewards for advances, close to 40% reduction for the guild season reward, and then every other season (50% less opportunity vs SOH which was every season). The Iridescent garden is also 40% reduced versus road to victory (only season end rewards apply).