So, you want to make some quick fame?  The very best way to do it is to conquer a few territories.  You will gain large amounts of population, districts, territory, and gain military kills.

It would be ideal if at least one of these could be disconnected from military conquest, else it will be the only optimal way to play the game (no diplomatic/peaceful tall players need apply).

My suggestion is to change the "Builder" star so that it's not based on the number of currently owned districts, but rather the total amount of industry your empire has spent on districts since the start of the game.  This would prevent you from retroactively 'claiming credit' for districts you conquered rather than constructed.  It's called the "builder" star after all, it shouldn't be earned via conquest.

It's pretty hard to disconnect the other 3, and perhaps you don't need to go further, but the Builder one seems an easy fix to help adjust the balance between wide/tall and militarist/builder empires.

Building on your idea, you could disconnect Agrarian by using the same metric as Builder, with food spent on pop growth?