Comment 10 for bug 1767826

You can compile a debug build from source using MSYS2 and work in KiCad without a debugger (it runs slowly when a debugger), then after KiCad crashes and windows "KiCad had stopped" dialog pops up, you can attach to KiCad process with mingw's gdb and get backtraces(but do not close the dialog).
GDB commands:

attach <KiCad process id>
set pagination off
set logging on
thread apply all bt
detach

Backtraces will be in gdb.txt in mingw working directory.

You can get "<KiCad process id>" from the task manager.
"set pagination off" makes so you don't have to press return to get all of the backtraces
"set logging on" will enable logging.
"thread apply all bt" will get backtraces of all threads.

That works for me on Windows 10, should work on Windows 7.