Many default VORS in MSFS do have the correct variation, but some such as EHK are incorrect apparently.
No, charted courses have absolutely nothing to do with magnetic heading. The two would only have corresponded the day the VOR was put into service. I have been working in the avionics field since 1974, primarily on aircraft navigation systems, but from 1990 to 1993 was a contractor for Thales electronics working as part of a crew upgrading several FAA VOR installations in the northeast and midwest. This is an area I which I have considerable hands-on professional experience.
In the case of EHK, and V293, the airway is defined as the line segment located 83 degrees clockwise from the VOR’s zero degree radial. That was true in 1965 and is still true today. The path over the ground that the airway follows is exactly the same today as it was 55 years ago. I don’t know if V293 itself existed in 1965 - it might depend on when the adjacent BCE VOR came online - and if it existed then, it might have had a different designator than V293.
But, whether it is part of a designated airway or not, the 083 radial, (and its corresponding ground path) is, and always has been, exactly 83 degrees clockwise of the VOR zero degree radial.
When you set the OBS in an aircraft to 083 degrees, the CDI needle will center when the detected phase differential between the zero degree radial and the aircraft position is 83 electrical degrees.
As I said before, the numbers on a chart are the OBS setting to use. Those numbers have absolutely nothing to do with magnetic heading. The CDI needle in the VOR indicator, combined with the OBS course selector are the only things required to fly a VOR radial. A compass or heading indicator is very helpful of course, but are not part of the VOR navigation system. If the chart numbers changed with magnetic variation changes, then they would no longer correspond to OBS settings, which would defeat the entire purpose of how a VOR is designed to work.
Here is the VFR sectional depiction of EHK, which clearly shows the angular relationship between the zero degree radial and V293. It is 83 degrees in 2020. It was 83 degrees in 1965. Neither EHK nor BCE has moved since then, so the line segment connecting the two VORs has always been 83 degrees clockwise from EHK’s zero degree radial.
