How do I identify a substituted font?

I have some Writer documents which were created on another machine. I have printed and circulated them, and now wish to make changes. I discover that the main body text font has been substituted, but I don’t know what font has been used as the substitute. I would like to set the main body text font to the one which is being used now, so that (a) new text is consistent with the existing text and (b) I don’t generate formatting changes to the parts of the documents which have not been changed.

I should add that I generally create documents in Writer then generate a PDF and circulate that so I can have some control over the look and feel of the documents on the varied target machines.

The only way I know of right now to identify a substituted font is to export to PDF,
and then use your PDF viewer to identify the font used in the text.
For example … highlight text, right-click, select font info.

There are some discussions in the bug lists about enhancing the substitutions interface.
This would include actually identifying the substituted font in the interface.

See: CONFIGURATION: Enhance Font Substitution Table

Thank you for the background - very helpful.

I recognize the necessity of font substitution. I can see that the decision of choosing which font to substitute for an unavailable font can be a complex one. But I can see no justification for LO making a change to my document and refusing to tell me what it has done!