Spawn event visuals don't appear

All the mobs listed were spawned in a cold biome. If the /summon ~~~~~ [insert spawn event] command is used, they often don’t change visually like they should according to the wiki, therefore it is not possible to summon different wolf, cow or sheep variants. If you summon a baby zombie, all the characteristics of the baby zombie apply and the zombie is very fast, although it uses the default adult zombie model. Most, but not every spawn event are affected by this, for example a wololo sheep is red, as it should be. Both the Wololo sheep and adult looking default cows that were created with the entity_born event can’t be bred. An entity_transformed cow looks default but can be bred. In summary a lot of the spawn events don’t work as they are supposed to do. Therefore it isn’t possible to bring some of the features into plains superflat worlds for example at the moment. https://minecraft.wiki/w/Spawn_event