Safety
sharkfin writes settings. It never writes firmware, so there is nothing to brick.
Settings land in the keyboard's own memory. Writing the same thing over and over can make the firmware stop answering, so sharkfin paces its writes, and a lighting slider writes when you let go. No write goes to a board whose command set is unknown. Writes need the cable.
If the board stops answering
Typing keeps working. Close sharkfin, unplug the cable, wait ten seconds, plug it back in. Fn + Esc held three seconds resets the board's own settings. Device, then Factory reset, clears everything on the board.
Backups
One file with the keymaps, lighting and settings. Not macros, not per-key paint. Back up before you rearrange things.