Additionally, you can use rich text label to get diferent colors in the same label
text = "[color=#ffffff]"+ tr("You killed ") + "[color=#d23931]" + str(enemyname) + "[color=#ffffff] +" + str(expe) + "[color=#f7a619] exp"
bbcode_text += text
text = "[color=#ffffff]" + tr(" You get ") + "[color=#f7a619] +" + str(gold) + "[color=#ffffff] gold[/color]"
bbcode_text += '\n' + text