Hi, I noticed that the heliostat mirrors actually lack any kind of explosion or impact effects, so I tinkered with the mod and created some of my own with 55 lines of code. I made a small fix to the tooltip image as well. Would you like a copy of my version? I am very unfamiliar with GitHub, but I can at least share a zip over Google Drive.
It adds the file prototype/explosion.lua, a few lines to data.lua and prototype/heliostat-mirror.lua, and a new changelog entry. Hope you find it useful!