Even if the lion king and the leopard goddess also worked for the World Union, they didn't live with human beings and other races than their beast race.
They only used the World Union to acquire some materials that they needed to cultivate their strength.
As long as they could become a legendary beast faster than other successors of the same bloodline, they didn't care even if they had to work for human beings.
Maybe these two cats were like that? And house cats should be super close to human beings. They might even have a master before they became sacred beasts.
Bello and Cellino understood the hidden meaning behind the question, but they only answered with vague hints here and there, never speaking clearly.
[Well, you won't know us, nyaaa~ We either stay indoors with our master or travel to faraway places.]