When I want to enter commands I'm using Guake terminal. Sometimes it doesn't show uo even I hit f12.
Why is it unstable?
Not sure how you mean, but from my experience I can say, Guake doesn't work straight away after boot, the 1bash need to run first and you will see notification about Guake(press F12).
Then you can press F12, after 1st run of 1Bash after reboot only Guake works normal with F12.
Hope it makes sense and helps!

Here's the scenario what happened earlier.
I wait 3 minutes for the system to fully load its daemon and programs and then I open up the guake (hit f12). After that I opened up the firefox and searched something (I often hit alt+tab to monitor if the miner still works).
When I'm about to check the watchdog, I can't access it anymore. So I hit f12 but no good. I clicked the launcher but it gives mo a "loading" mouse.
I made a workaround for now, I went to guake properties and put the window "always on top".