Even in this case, the check doesn’t add any value.
If the last backup failed, the log should state the error. If the error is “Unreachable host”, it means the host was down at backup time not right now while I’m checking it. Thus, clicking on “Check destination” can tell you that the host is now online but not what really happened during the backup.
You can do a better check (is the host reachable and is the destination writable) just clicking on the “Edit” button.
Don’t get me wrong, we are really really pleased to receive contributions (see this thread as an example)! But we should avoid the feature bloat, especially on the core.
A patch like this one, will add roughly 200 lines of code which should be maintained by developers for years 