The right translation is “instrument”.
This is generally correct. The etymology is the word Indriya comes from Indh which means power. The indriyas are the instruments that are coordinated by a natural power that controls them.
We are said to have ten indriyas
The manas is included amongst the indriyas so they are said to be 11 indriyas(5 jnanaindriyas, 5 karmaindriyas and 1 manas)
There are also said to be three internal indriyas, manas or lower mind, ahamkara, the “I” sense, and buddhi, the instrument of discrimination. It would stand to reason that if these three are instruments, there must be some corresponding potential that they perceive. Inexplicably though, Samkhya does not define these potentials as separate from the instruments that perceive them.
These are not called indriyas. These are rather the powers behind the indriyas and control the indriyas. The part that controls it is the ahamkara(the self-reference faculty) which gives the sense of personal identity, which is turn is made out of the discrimination faculty. This is like an executive program which receives information organized and sorted by the manas, personalises it through personal identity filters and then makes a judgement and acts on it through controlling the indriyas.
Didn’t ancient Greeks speak about something similar, something they called “Logos”?
Yes, they in turn got their logos concept from the notion of shabda-Brahman in the Vedas and is represented as the sound of OM. In the beginning there is a vibration which sets the world into motion and causes it to evolve into being. In Kashmir Shivaism this is known as spanda. In Samkhya this is explained as the the breaking of of the balance of the gunas in the beginning. In the Rig Veda it is described in the Nasadiya sukta as in the beginning the divine will arose which causes manifest beingness.