I had this same problem but managed to find a fix.
My site was set to British English, en_GB. Changing the overall site language to en_US in the wp-config file forced the plugin to use the US language.
If you want to still keep your original site language, you can copy deefusereorder-en_US.mo and deefusereorder-en_US.po from the /languages folder in the plugin’s directory and rename them to suit your language.
For instance I’ve copied them and renamed them deefusereorder-en_GB.po and deefusereorder-en_GB.mo and now I’ve got the plugin in English again.
