That would not work because the string would still be there in Orchard Core?

It would try to still find a string that has that \r\n

@S["Something\r\n"]

If you ignore it then that string will never match any translated PO string.

That would not work because the string would still be there in Orchard Core?

Could you please elaborate?

It would try to still find a string that has that \r\n

There's no string in OC has \r\n

OC or not. When you use the POExtractor it will extract strings in code.
If you escape \r­ from the POExtractor then it will create a string in the resulting PO file that doesn't contain it.
Which means that it will never match anything from your code.

@t["Something \r\n"] --> in your C# code will become

msgid "Something \n"

Then when you try to load translations it will try to find a matching string for "Something \r\n" still which will result in that string to never be translated unless you remove the "\r" from your code. Here, you need to warn the user that you found a "\r" in the code and that you escaped it else the user will never know about it.

We might log a warning when the user is using \r only

@Skrypt, anything to add here, or shall I merge coz I need to bump the package