Interrupter brakes require the brake cable to angle away from the bar to meet the lever at the proper point as shown in the picture below. You can see the handlebar tape doesn't carry on closer to the center because if it did, and was wrapped tight, it would put a harsh bend in the cable. But it seems the right tiny bit of molded plastic to guide the cable off the bar right into the interrupters at the correct angle (shown in red on the left) would allow you to wrap the tape nice and tight right up to where the interrupter levers clamp on the bar.
Is there such a cable guide wedge thing? If not, has anyone made their own? It would be nice to bring the handlebar tape nicely finished right up against the interrupter clamp.