I think it is possible to replace it ( lever ) pretty certain but check
It is on a brake a handle with an adjustment screw akin that seen in enclosed first picture
handle pivoting around a bolt
A Mechanical system separated from the Hydraulic system
If you take off the pivoting bolt in such a brake system the handle will come off
Without brake fluid leak
And if it can come off a replacement can go in
If one can find a lever that fits.