Found the source where the task order is explained:
https://forums.frontier.co.uk/threads/helpful-information-on-zookeepers.528619/
So give the cleaning less importants is something by design from the begin of release.
https://forums.frontier.co.uk/threads/helpful-information-on-zookeepers.528619/
Keepers always enter a habitat and inspect before doing anything else. If animals need water they will deal with this immediately. If they need food the keeper will leave the habitat (this is normal) and go to the closest keeper hut to prepare food before returning to feed – this is why keeping keeper huts and habitat gates in close proximity is so important. If there are no more pressing jobs the keeper may choose to clean the habitat, keepers will normally clean habitats after feeding.
So give the cleaning less importants is something by design from the begin of release.