steddy!!
In most instances magnetic angles are printed on the chart except at latitudes/locations where magvar considerations make it more sensible to print true values.
Either way the angle at each end of the track won't necessarily be the reciprocal of the other. Over long distances we prefer to fly geodesic paths and north-seeking needles do not actually point directly to the Magnetic North Pole until you are very, very close. So there may be a slight (1 degree?) inconsistency every now and then between paper and glass. But stop a moment. Surely waypoints et al are strictly defined by latitude and longitude and not by the whims of geomagnetism or how many stubbies the cartographer had for lunch?
I don't think for a moment that the preferred mode of navigation in a modern transport aircraft is predicated on paper and glass magnetic values. Might it not have more to do with a suite of inertial and radio aids that attempt to place the aircraft on geodesic paths on a largely known spheroidal earth between points whose coordinates are fixed?
Don’t obsess with magnetic values even when it comes to the hemispherical rule. Depending on whether ones instinctive oath is to say merde or sh!t there have to be exemptions of one sense or another and fun to be had if drinks are not to be spilled. So it will be writ somewhere in the AIS in such a way that you can only find it when you don’t need to.
If you don’t like what the compass says, hang your jacket over it and never trust your instruments if your tie points at the ceiling. Based on not much more than this I never landed at the wrong airfield.
Alas for Jepps they are nowadays almost strong enough to make paper darts. Dost thou remember when they were illegible blue flimsies but of strength sufficient for certain, ahem, sedentary purposes? Now you couldn’t do THAT with Aerads!