It depends on exactly how you setup your second profile. If you used a name tag for each profile that is different then the two profiles are using completely isolated databases and any library changes, update or clean, will have to be done on each individually. This is currently what you have to do if you want independent watch status.
If you don’t mind sharing a watch status and only want to restrict what is viewable on the Kids profile then you could instead keep the kids content in a separate location linked to with a separate share and then use locks to hide everything other than that from the kids profile which still having it attached (and thus maintained) to the master users profile. I wrote a guide on this you can find [here] if your interested. Alternatively you can tweak nodes to filter what is shown on the Kids profile without separating off your media but that is a bit more involved and is dependent on what skin your using. The OSMC skin allows for this sort of thing, Kodi’s default Estuary skin does not.