Yes, that's always a problem with nonstandard fonts. We use an "architectural" hand style font which has, for example, the semicolon for a plus-or-minus symbol and the tilde for a diameter symbol. There are a fair number of keyboard characters that are never needed in architectural notes.
You pretty much always need to give any custom fonts to others along with your drawings. Not only because of special characters, but also to preserve the general look and formatting. No two fonts have the same letter size, line spacing, etc., so replacing one with another will usually lead to some pretty messy text formatting.
It's simplest to just make a list of the custom fonts you use, and always give all of them to anyone receiving your files. Tell them to pace them in the same folder with the drawing, and they'll always work.