For even ripening, I have had good results by picking mine green and then letting them sit in warm environment about 74 to 100 F for up to 7 days. I eat them when the outside skin is still a green look but the flesh is now orange after the about 5-7 days when I notice a little softness. This method may actually decrease the tartness and overall taste a little as well so not quite as much kick. But, they are still good and IMO better than eating uneven tree ripened sweet tarts with too ripe and not ripe enough areas.
My tree ripened ones have been uneven ripening and or split.