Did you drill the hole in the frame for the lamp wire yourself or was it there before? The lamp looks like a generic supermarket incandescent. Is that right?
All the Romet folders seem to come with the holes in them, with a rubber grommet to keep things tidy and the wire from moving/wearing. All one needs is a straightened out wire coat hanger with the wire taped to it to get it through to the fold - and a warm enough day to make the grommet to 'cooperate'.
The lamp indeed does resemble an incandescent, I had never thought of them like that. These bikes came fitted with many different types of lamps since they first rolled down the production lines in the 1970s, but mine were some of the last and came with these absolute minimalistic units. Although they are cheap units I have kind of grown fond of them...
About 5-10 years older than mine, with the same wiring holes in the frame and less minimalistic front lamp