By design dbFront uses existing database structure to generate its UI. The expectation is that the DBA will have the required access to make the appropriate changes.
At the same time I fully understand your specific use-case and have encounter similar situations with ERP or Financial software packages.
At the moment the solution is to use a table alias or other means to make specific tables available in another schema where changes can be made. This is not ideal.
The proper solution would be to allow users like yourself to add the missing structure information.
NOTE: Please vote on this Feature Request if it interests you.