The path to Aethyr is too hard for players to find

3-4 NPCs in Frostia give vague hints that it's west or north west. One even says that it is "west of the old village" but players will probably think this means the Isbamuth place. And that place cannot be revisited again.

Neither poppet nor andulka know/knew the path, only us code-readers could find it.

Plus, there seem to be some additional requirements that you blackboxed, as franzo could not pass with me.

If you feel that code-readers have an advantage then that is an incentive to fix the NPCs to give players better hints, not to withold code!