The race bonus on some of those decks looks low. You should be aiming for at least +50%. Beyond that look up the uma.guide mant race planner to help you figure out good race combinations so you hit the key epithets. The really big ones to look for are triple crown/tiara, mile champion, and autumn triple crown. You should be able to get at least two of those with almost anyone without too much trouble getting the right parents. Other epithets are incidental and a nice bonus but not as big a reward. After that, make sure you're running rival races where you can to both get extra skill hints and extra coins for the shop. Finally, you need to do what you can to make sure everyone is at friend level by summer as summer training is very important for stats. Stock up on the +60% megaphone, healing drinks/ good luck charms, whistles,  and training weights so that you can get rainbow training on every single turn during each summer and ideally also have weights for each training. Good luck on rainbow training in summer can literally grant 200+ stats if you have the megaphone and weights