Like the kind you get underneath a mispeled :dubious: word in Word. Most diacritical marks and editorial marks have old, if not often commonly used, names. But I wonder if the squiggly lines are so recent that they never had any “offical” designation.
Microsoft calls them “wavy underlines”:
In heraldry, such a wavy line on a shield or coat of arms is called “undy”.
The misspelled underline is more zig-zag than undy. I’m trying to remember, is that engrailled? Nope. Per these guys it’s indented.