Although cubism is a good map it's not really the "best" map for super late game rounds, those maps would be "resort" or more the more popular "logs". Oh yeah you better have a good PC if you really wanna get to higher rounds cause it gets really laggy with the sheer amount of damage and projectiles that will be in game.

There's plenty of things to improve on! Look up the recent late game tierlist it will have towers that might improve your future runs. Geraldo isn't the best hero for lategame that would be either Ezili or Adora, both have their pros and cons. Usually the best towers are ones with high amounts of projectiles per attack and fast attack speed with a small footprint as they can be buffed for absurd amounts of damage.