First is is completely unsupported to query the tables, only the supported Sql views can be used. Why because record locking can occur, causing Sql to "kill" the wrong thread, thereby causing all sorts of problems.
Second, it is unsupported to edit the db in anyway. Doing so may cause problems when you upgrade to a newer version. If the cm team disabled something there is a reason for it.
Third it looks like you are using the old connector if you are using the SCCM 2012 connector. As there is a SCCM 2016 version. https://www.enhansoft.com/how-to-integrate-sccm-data-with-service now/
At the end of the day, i would grab your MS TAM and your Servicenow TAM and get them together to work on your problem so that everything is fully supported.