jsg, Thanks. I am very familiar with Find/Change (Interpolate).
Susan G, Thanks. I had partial success. If I use Fb? => E?, it seems to work, whereas Fb5 => E5 does not. In fact, the Find/Change box changes the E5 to Fb5 in the dialog box. You can see this happen as you hit enter and when you go back to the function.
Using ? makes the function more limited, but I suppose one could do a Filter first to select only a specific octave. So thanks for the suggestion: there is still a bug here but at least this will take care of many problems.
NOTE: The Find/Change box will not accept bb (double-flat) so there is no solution for that.