A lot of moving parts here, but I've lived through similar transitions and can give you some things to think about:
First thing is that you probably have to sub out the fonts in two places. First is the paragraph and character styles, which is the easiest. My suggestion would be to create a new document with the new styles. These styles should have the same names as the old ones, but using the new font. So when the old document is opened (and I don't know of any way around that), you load the new styles. If your typography is based on style sheets, a lot of the old fonts will be updated at this point.
The second step is to search out the places where the old fonts have been applied as an override to the style sheet.
Style-loading and font-replacing can certainly be done in a script. I would recommend making it an event-listener script that fires whenever a document is opened. Way better than a sticky note that says "Remember to sub out the fonts."
A script also might be able to help with text re-flow, but that kind of depends on what you mean by "fix." I could imagine a script that resizes text frames to make the new type fit, but at some point you'll probably want human eyeballs on it.
Maybe your font manager can do some or all of this for you. I am blissfully ignorant of such things. The idea of letting the old fonts go missing, it seems to me, is the first step toward letting the font manager do the swapping. But if it means that somone has to pair up a missing font with a new one, I think you'd be better off to leave the old fonts installed then run a script that already knows which new fonts go where. Then, when all the old docs have been converted, you can give the old fonts a decent burial.
Thanks so much Robert,
Many of the most important docs dont have Style Sheets . They're only 1-2 pages such as book covers. I know I can do "Open" then "FInd Font"
Oops! Bumped send button by accident!
I looked into "Universal Type Server 3 Core Scripting Guide" and don't see anything about replacing fonts.
If I can't script the "Find Font" command (are there any already out there?) then at least I'd like to be able to script, or find a shortcut to, resizing boxes with text overflow symbols in them.
There's no findFont, afaik, but you can use findText/changeText to the same thing
app.findTextPreferences = app.changeTextPreferences = null; // clears any old settings
app.findTextPreferences.appliedFont=(a reference to the old font);
app.changeTextPreferences.appliedFont=(a reference to the new one);
Then it's a matter of looping through the text frames, looking for
app.activeDocument.textFrames[i].overflows == true
And then apply whatever logic you like to resizing it. I might start with FitOptions.FRAME_TO_CONTENT but that would be where you need the human eyes.