TSB image identified corrupt should be fed and output word versions of the date as opposed to its current purely numerical equivalent/version. Without looking at the source code, the current version can cause vast confusion.
It would be best to use https://commons.wikimedia.org/wiki/Template:ISOdate for this as it handles localization automagically.
Template now takes an ISO date as |date=, or as the existing |year= |month= |day=.
Works now. Thanks @AntiCompositeNumber ! (Also thanks for adding the backwards compatibility.)