What about stuff like Efl.Loop_Timer.time_pending?

It is a "value-less" property where the getter's return happens to be the "value" of the property.

Shouldn't cases like this be modeled as a single-valued property with an empty get?

Holy F.
That totally looks like it should be fixed in the eo file (add the missing values and remove the return).
The C API would not change so I think we can safely do this even when the method is not @beta.

Additionally, should Eolian error out upon finding value-less properties? @q66?

Hm, I guess it should check it. I'll look into it and see how viable it is. If we can't change it it shouldn't be a big deal though.