You only need to fit proper brake levers on your handlebars,
then fit those interrupter levers where they belong, in the middle of the cable.

because they were not made to be on the end of the cable,
they flex the soldered stiff portion where the ball on the end of the cable is,
every time you apply the brake. Danger!

A proper lever for that location, end of the cable,
the cable end pivot lets that flexing happen in the lever,
not bending the stiff section of the cable, to breakage.

Road bike aero brake levers, 2 + the interrupter levers, 2,
in the middle of the housing, end of the tape job..
the cable runs thru the lever, nonstop.