when I switched from Quicken some years back I imported a lot of transactions that had memo fields including words with diacritical characters (e.g. "é"). Gnucash replaced those characters with a question mark. A search-and-replace function would automate an impractical,manual process to clean up my data.

Find and replace would be very beneficial

Any plans to add this functionality? It's one of the missing things that makes Gnucash rather tedious to use when compared with other similar applications.

very useful......

Yes. It's why I'm still using Quicken rather than Gnucash.