fényen
Fényen is the locative form of the Hungarian noun fény (light). It marks a position on or at the surface of light, reflecting one of the surface-oriented locative endings in Hungarian, typically -on/-en/-ön. In contemporary usage, the most common expression for “in the light” is fényben. The form fényen appears mainly in literary, poetic, or archaic contexts and in some dialectal usages.
Because fényen conveys light as a surface or plane, it is primarily a stylistic or imagery-driven choice
In summary, fényen is a legitimate Hungarian locative variant of fény used chiefly for poetic or historical