The lucite strip is a very interesting detail; never seen that before in an O scale car but have seen something similar in HO (Marklin and other dining cars). These days you could use side-reflecting fiber optic strands or individual LEDS for table lamps, although the latter option (which I have done) is not very cheap in terms of time or components.
I'd speculate that if it was intended that in this car the table lamps would show as lighted, other lighting would be minimal (or not used) so as not to drown them out. You may want to consider that in making your lighting modifications. Also, looks like the car was produced before the days of things like GRJ's passenger car LED lighting kits, which allow you to adjust the brightness of the lighting. (Intentional but well deserved plug - I have used several of these kits, sometimes for lighting projects GRJ could never have designed them for.)
In any case, domes and dining cars don't as good as they might without some form of direct lighting, which can be overhead or (in domes) at floor level. I prefer the latter, but put both in the last dome I did, a Lionel UP excursion car. Overhead and floor lighting was overkill, but the dome was intended to look like an aquarium or Christmas Tree and does: