Salesforce API module encryption warning
This is most likely related to AES encryption on your Salesforce credential data, not the connection itself. From the relevant doc page:


  By default, all Salesforce credentials are stored in the variables table, unencrypted. If this is a problem for you, this module supports encryption via the AES module


When you have the AES module enabled (which it seems like you do), the message you see in your site status report is:


  Salesforce encryption is enabled but not configured securely.


And if AES is not enabled, you see this instead:


  Encryption is unavailable. Using encryption is recommended in order to better secure your data.


Check out salesforce_api_requirements() and salesforce_api_encryption_available() for more. From the logic in the latter it looks like there was an attempt to return more useful information (specifically about the AES module) along with that generic "salesforce encryption" message, but for whatever reason that text never propagated up to what was printed to the screen.