You might be right. Just checked the EuroBones page and it said,

Points are not earned on flights operated by another airline on behalf of Lufthansa.

However, in reality there is a difference between a regular codeshare flight , with e.g. United and LH flight number, on which United holds the risk, and a EW flight which operated solely for Lufthansa.

For Lufthansa itsself it does not make a difference, whether LH mainline or Eurowings operate the flight, as LH holds the risk. Lufthansa even shuffles around these planes as they like. So if you book a mainline LH flight, you might be able to end up on EW or CL.