Sender Certificate Based Authentication Externalization: Standard Integration Flows vs. Custom Flows

Dear experts,

I have realized that for prepackaged standard integration flows "Authorization" is available as option in the the "Sender System" of an Integration Flow.

This is configurable and even the client certificate can be selected when configuring the Integration Flow thus the certificate can be changed without touching the Integration Flow itself:

However when creating a custom flow authorization needs to be configured in the sender channel (thus the connection between sender system and the first flow step), and no option is available for the sender system:

The difference seems to be now that the authentication method (basic vs. certificate) can be externalized, but not the certificate itself.

Does anyone know why there seems to be a different design and functionality? Is there any possibility to make certificates itself configurable in custom flows? I know it can be achieved with certificate-to-user mappings but I would rather prefer to have the same configuration option as in standard flows.

Thank you for your advice!