A font can be correctly installed and structurally valid yet lack a character your document needs. Reinstalling it repeatedly will not establish whether that character belongs to its repertoire. Inspect coverage before substituting another symbol or changing the text’s intended meaning.

Keep a copy of the exact required text from a trustworthy source. Include the troublesome symbol and a few surrounding characters. Similar-looking marks can have different meanings, so avoid recreating the sample by choosing whichever keyboard character appears closest.

Inspect the selected font’s repertoire

In Font Book’s Grid view, double-click the font to inspect its Repertoire of characters and symbols. Double-click a character in Repertoire and use Copy when you need that exact available character. In Sample view, double-click the sample sentence and enter your own text.

List view exposes the available styles beneath a font name. Apple’s Info button provides details including language support, manufacturer and file location. Record the family and style you are investigating rather than treating every similarly named font as the same file.

Compare the required character with the actual repertoire and the custom sample. A normal-looking line in another application is not, by itself, proof that every glyph came from the named font. Keep the coverage enquiry tied to Font Book’s specific font entry.

Choose a correction that preserves the text

If the required character is absent, identify a legitimate font that supports the intended text and fits the project’s requirements. Do not silently replace a mathematical operator, currency sign or letter with a visually similar character simply to remove an empty box.

Apply the candidate family and style to a small working copy of the document. Inspect the target character in context, along with neighbouring spacing, weight and line breaks. A font that supplies the symbol can still change the layout enough to need a deliberate design adjustment.

Check the actual deliverable after export or handover, especially when another device or application will render it. Keep the confirmed text and selected font identity in the working notes so later editors can reproduce the choice. This investigation answers whether the font contains the needed character; file validation, pronunciation and the final document’s rendering remain related but separate checks.

References: Apple: font repertoire and previews.