The F12 view is displaying the table names. It has the security context of the user logged in (or anonymous user if enabled). If your Entity Access settings are secure, so is your data. Using XPath in the Entity Access settings helps.
Writing validation Microflows on the string that needs to be stored can be used to detect abnormalities and to refuse the storing of the data server-side.
If you are using the SQL Connector to interact data with another database, you can use this blog https://www.mendix.com/blog/mendix-8-10-making-life-better/ to find your answers.
Go Make It.