You can have an array column of emails to not have another app, let’s say “email 1” stores the user’s email, “email 2” is automatically populated by the admin email when “email 1” is not empty. Then set the row owner on that array column in the Editor.
I actually did this same thing a while ago for a post on here, you can see the idea here. Duplicate the sheet and show only last 25 feedback items by each user in the app. I don’t think you need to delete it, 25000 rows is not much for a Sheet, the maximum cells they can hold is 5 million, it’s more of a bottleneck in the connection between Glide and Sheets, but as long as you keep it to only last 25 I don’t think there would be a problem.