Hi Peter,
Almost* all text in the DSpace User Interface can be found in the translation/internationalization files in the "src/assets/i18n" folder:
https://github.com/DSpace/dspace-angular/tree/main/src/assets/i18n
This means that you can easily make bulk changes across the English file (en.json5) as you see fit.
(* I said "Almost" because we do occasionally find areas where English text is wrongly hardcoded. These would be considered bugs, as the goal is that all text should be translatable.)
Tim