If
a document uses fonts not installed on your system, an alert message
appears when you open it. Illustrator indicates which fonts are
missing and substitutes missing fonts with available matching fonts.
To substitute missing fonts with a different
font, select the text that uses the missing font and apply any other
available font.
To make missing fonts available in Illustrator, either
install the missing fonts on your system or activate the missing
fonts using a font management application.
To highlight substituted fonts in pink, choose File >
Document Setup, and choose Type from the pop‑up menu at the top
of the dialog box. Then select Substituted Fonts, and then click OK.