The command /banwave add Player is ambiguous (same command to add tempban and permaban, resulting in it all being interpreted as tempban). Otherwise solid. Waiting for fix :)
You can always replace the time argument with "perm" to make it permanent but for servers on older versions the tab complete specifying this may not have been apparent so I'll make an update to the plugin this weekend to add support for both a new command whilst keeping the old method for legacy support. In future make requests like these in the discord for rapid responses as I hardly check reviews for the plugins but thanks for your feedback.