Bad exemple, FInal Fantasy 6 actually can randomly freeze when played unpatched on a PAL console, most notably when opening the menu if my memory is right. But there's a patch making it run fine.
Chrono Trigger works perfect on a PAL console.
On the top of that, you have to add games that explicitly refuses to boot if they detect a PPU from the wrong region. This security can be there or absent regardless of whether the game runs well or not on a console from the wrong region. For example Donkey Kong Country refuses to run on the wrong region, but it would work just fine. Here in PAL lands we have unofficials adaptors that allows us to play a NTSC game on a PAL console by using the CIC from the PAL game, and some of the adaptors also makes the SNES game belive it runs on a NTSC console, but this breaks some PAL games.
This is very confusing to explain.
You also have to know that most of the world did not get official releases in their respective countries and either had to import from richer countries or to use clones.Brazil uses 60Hz video. Labelling it "PAL" is pedantically true but misleading.
Indeed the French gaming material are just PAL consoles and games. Some games had an horrendoulsly bad French translation (*). If anything the video signal was modified at a latter stage, or perhaps there was modified PAL consoles. In call cases, just like PAL-M, it is irrelevant for software. As such, I agree using "50Hz" and "60Hz" makes more sense than talking about NTSC and PAL.I'm fairly sure there is no SECAM SNES it's just a PAL one.
(*) It makes me laugh when the American public complains how retro games were poorly translated from Japanese to English, because what we got was much, much worse.