The gathering of summon crystals could stand to at least be a little faster if not much faster. With so many characters(and more presumably coming) and the draws being random it is painfully slow. The level ups could probably have more significant impact as a +1 bonus per level barely makes a difference and even getting levels is tedious due to the randomness. Could even say like you get the +1 to all and get an additional +2 to add to a stat of your choice so you can customize the characters you like some more. Or at least have a way to summon the characters you actually want, like pay x crystals to get a certain character or you can put a custom summon banner of characters you already own together so you can draw from a smaller of pool of characters you actually want to strengthen instead of the entire roster. I get it's a gacha style game but it's asking for a lot of time if you actually wanna progress :p
Minor gripes aside though had fun, fun game, cute characters as always :3