Well, without the lit tag it cannot be determined if the maxspeed:type=sign designation is correct, so it makes sense to remove this tag pending the addition of a lit tag before a maxspeed:type tag. From my experience it's more likely a lit tag is correct than a maxspeed:type tag on a 30mph road.

And yes, technically the road can be lit, with the streetlights further than 183m apart, and not be under a 30mph speed limit, however it is impossible to tell without measuring the gaps between street lights. Large distances are unlikely to also warrant a lit=yes tag anyway. There is a village near me that has a few street lights on a 30mph road, and yet there are repeater signs so it does not qualify as a restricted road, so that's one way of telling.