IANAL nor intelligent, but after skimming the text of the directive I felt like the definition of damage is very limited. In particular, if I understand correctly:

our business to lose this giant contract

would not be covered by this directive, this directive is only about a human being hurt in some way,

thousands of consumers left with bricked devices

would be covered in case of “your game installs a kernel-level anticheat and the anticheat breaks PCs”, but not in the case of “you uploaded an upgrade to a firmware of the washing machine you produced and it bricked the machines”; the directive is not about a product breaking, but about the product breaking your health, other property or data,

my washing machine to eat my dog

is basically the exact case this directive covers.

It seems OP wanted to pass the file name to -k, but this parameter takes the password itself and not a filename:

       -k password
           The password to derive the key from. This is for compatibility with previous versions of OpenSSL. Superseded by the -pass argument.

So, as I understand, the password would be not the first line of /etc/ssl/private/etcBackup.key, but the string /etc/ssl/private/etcBackup.key itself. It seems that -kfile /etc/ssl/private/etcBackup.key or -pass file:/etc/ssl/private/etcBackup.key is what OP wanted to use.