Character encoding error

[Mystical_Dazzle5FC6]

In a report document I have created there are graphs which I designed in illustrator and imported as eps files into the indesign file. Our brand uses the font 'realist' and the stylistic set one. When I run an accessibilty check this is flagging up a character encoding error, but only with the labels in the graphs. The rest of the copy in indesign itself is fine. I have made sure fonts are emdedded when saving the graph files. I don't really want to have the graphs copied and pasted from illustrator into indesign, nor do i want to use a different font. Has anyone found a solution to this problem please?