I would like you to increase the rewards for the championships the higher up you are. Currently I think the amount of the rewards stay the same after like the 20th level. I would also like you to change the championship structures a bit. Top 3 get a 1 level promotion. 4-9 stay in the same championship. 10-14 get relegated and depromoted 1 level.
I would like to have the possibility to buy more builders I already have three but it should be possible to buy upto at least five builders.

Bad idea for the 4-9. It might mean not enough participants for other leagues. I'd say top 3 do go yes,but 4-6 or 7 can go up but not skipping 1 league. Since 14 members relegation 12-14 place.
Yes also 5 builders is ok but gold ball prices will increase which will be almost impossible to afford

Plus you cant earn enough money to keep three builders busy let alone 5. no one in their right mind would waste gold balls on builders they cannot utilise.

Relegating players would not work either as it would be unfair on a lower level to suddenly have three teams appear with far superior skills appear each season.

Currently, the top level increases by one each season, so in reality, if you get a single promotion you are really only just standing still. if you fail to get promoted you become one level further away from the top. this is the equavalent of a demotion without the impact occurring occuring on the lower levels. a pretty good compromise in my eyes.

Why in real life teams go down that are or should be better than those in the league the join in other games it worked ok & anybody relegated is no doubt relegated because their team is not that good.

Maybe sometimes a 4th builder would be ok & could be kept occupied but for how long once building things reach level 20 your income is strained to even keep 3 on the go

1 mistake: Real life and computer game is 2 different things

BUT,maybe 4th can be orite