trying to set-up httpS (with Stunnel)

[Mars]

this is quite normal, all connexctions transiting through STUNNEL are identified in local mode (127.0.0.1) by hfs, there is nothing to do to change this situation.

[rejetto]

I watched closely the connections log in HFS... an address would flash very briefly...

that's not the log. The log is on the right (you get a "log" label on it, indeed).
You are looking at the bottom, that's the connections panel, that's not persistent (unless you right click and enable "leave...", but ensure you disable it after a while, to not get flooded).

connected via 127.0.0.1. This doesn't seem right.

sadly that's how stunnel works.

future: HFS 3 is expected to support https.