Is it still unsafe to update your game if you have CC?

If you’re talking strictly about CC, it’s only the odd piece that gets broken by an update. I have CC content from 4-6 years ago that works just fine, including clothes, skins, carpets, paint, curtains, etc.

Even if you have a broken piece of CC it typically doesn’t have disastrous results.

It’s far more common for script mods to break with patches than CC. Stuff like MCCC, More Columns, UI Extensions, etc. And if one of these is out of date you can experience extreme weirdness and crashing.