Wide characters (e.g. Tildes ~) overflow on signs

Signs have limit to the amount of characters on a sign so that they don't glitch of the side of the sign. When using a large amount of tildes (eg for seperators or decoration) they glitch off the sign, creating floating text.

The effect can be seen in the attached image.

My theory as to why they do this is although they obey the limit of 15 characters per line, they seem to have a larger amount of pixel per letter (wide) meaning that they eventually glitch off the sign. The image shows that all other characters a closer together, while the tildes are further apart.