Maybe the issue here is the shadows and not the luminous gauges.
Take a watch with luminous hands and charge it in the bright sun for a minute, then take that watch into a very dark room. It's amazing how bright they "shine".
So, the instruments in DCS look fine against the very dark background.
However, the shadows in your 109 screenshot seem very sharp, with no gradient between shadowed areas and lit areas. My shadows look quite different, they gently transition from dark to ilght areas.
It's as though the shadow areas in your 109 screenshot are taken from inside a small room with no windows, and then, 1cm away there is bright sunlight. This makes the luminosity look out of place as a result.
The solution might be to change cockpit lighting, shadows, deferred shading and SSLR settings.
Turn Cockpit Global Illumination on too.
The image below is what my spitfire cockpit looks like in half-shadow half-sun. Note the smoother shadow transition and the more gentle contrast on the instruments in the shade compared to yours.