Serren: CloneKeen/Commander Genius are not source ports, they are engine/interpreter recreations.
It's a open source clone, yes.
https://gitlab.com/Dringgstein/Commander-Genius/blob/master/README.in:
Commander Genius is an open-source clone of Commander Keen (1-6, Dreams) which
allows you to play these episodes and some of the mods made for them.
Yes, it does interpretations.
What does Commander Genius do then? Interpreting those games on modern systems, that's all basically.
And you're right, since it's not based the original sources it's not technically correct to use 'port or 'source port'. Just like it's not technically correct to use emulator on Wine f.ex. :)