Sadly this is an open issue and not yet fixed in JSON Forms. Internally we use . as the object separator. The clean fix to use an array of path segments instead however is not straightforward as a naive implementation breaks our caching/memo. Therefore we plan to fix this only after the 3.0 release which is of higher priority atm.
As a workaround you can escape the dots with something else before handing the schema over to JSON Forms and then transform the data you get out of JSON Forms. Note that if you manage your UI Schema manually you will then need to use the escaped property names within the scopes.