Hi Boubou,
I absolutely understand your worries.
In Reaper, you can have different keyboard assignment for actions in recording mode.
Look in Actions window, typically you'll be in "Main" section. You can see it in top right dropdown menu in Action window. There you can select "Main (alt recording)" and remove all (I mean all dangerous) keyboard shortcuts and leave only few essentials, or you can assign stop action some hard to press key combination (something like Ctrl+Alt+Win+Shift+Esc you know
Then in 'play' mode everything works as usual, but when recording (in 'record' mode) only key shortcuts assigned for this mode are active