If they are old 404s, the benefit of managing it now is going to be minimal as Google is likely to have relegated the pages as non-valuable. The main case I say for dealing with them is to correct live traffic going to them OR capture backlinks pointing to them. Either case, you’d want to setup a redirect from the old page to the new version. If there is no new version of the page, then it’s legitimate to let it stay as a 404.
Being another owner, if you can’t deduce the content of the page form the old URL handle, you could use https://archive.org/web/ to see the page’s contents to then redirect it to an accurate version.