You should make tetrad and theme the same object and make them white (in the sprite editor window), then change the color on the properties bar (left side).
Also, doing this saves you having to create multiple objects for each color, if you still want to tell them apart, you can use the UID or create an instance variable.
On your current version the object.colorValue of theme and tetread are 0,0,0 (It is the color value of the properties bar) mainTXT stays the same.