Globe brightness in a pinball machine tends to be a personal preference and also depends on where the machine is being used. Most pinball machines were designed to be used in arcades that are usually well lit. When a pinball machine is used at home the lighting can be very different. The mini-domes arranged above the playfield on the Data East Simpsons machine were way too bright for my liking even with the standard #89 incandescent globes. When replaced with #89 LEDs they were slightly brighter again. There was some improvement when the LEDs matched the same colour as the domes (rather the white) but still too bright.
My solution was to use some sort or filter/diffuser inside the dome. I ended up using the casings from old fluorescent starters. By cutting them down slightly with a hacksaw they fit snugly over the LED. Then with the dome re-installed the light is nicely diffused and much easier on the eyes.
Here are a few photos to illustrate the process..