So long as you put Steam in Offline Mode and never got to online mode again, it ought not to break the mod since the folder digital "name" has already been altered by Steam from what the mod-creator would have originally had.
But that's not really a very practical "So long as you .."
The digital "name" of the folders you see are actually the Steam ID numbers of the various workshop content pages.
If you rename the folder Steam would likely think it needs to re-download the mod, in which case there would be two mods in your list with the same *.modinfo filename and GUID, which is bound to cause issues of some sort.
We can all thank Steam for the stupidity of using Content ID #s as the folder names instead of the Name of the mod as shown in the modinfo file which btw is used by steam to set the mod "name" in the Workshop browser listings anyway when the mod is uploaded to the Workshop.