Customer selections can be imported back into your workflow in various ways. Transcribing numbers is definitely a thing of the past.
Export via web application
Select the desired customer selection
Click on the 3 points menu/Export
Choose your desired export format
Then go to this folder in the Finder and paste the selection into the search box
Now you can edit these images and make them available to the customer again. (Possibly adjust the permissions so that the customer can also download the edited images).
In Capture One in the right catalog under search, paste the clipboard and the catalog will be filtered to the selection.
In Lightroom, the images can also be filtered via the search. However, there is a possibility here with the plug-in without the export step in the web application.
For this under Library/Plug-in Extras/Import selection
Import selection dialog
Select desired customer and project
Under Selection you have several options
The customer selection
All completed selections
Now you have all the images filtered to the customer selection. You can now rate them with stars, create color labels, add tags or save them to an album.