
I'd like to contest this. The 'anglicised' argument sounds like an invention of someone's imagination in order to justify why they spell it wrong.
Drindl gets 610 Google hits total. In English it's found 281 times, in German 268 times. I don't think the Germans are referring to any anglicised spelling. It's not in any dictionary I've found, including the OED. Google also brings up AdWords for dirndl if you type drindl, showing that Germans are aware that people type it wrong. Many pages which have drindl have it once or twice and the rest of the page refers to dirndl... thus clearly a typographical error. For example: Gillian Bowditch at The Scotsman uses both. It's just sloppy.
Dirndl, by contrast, has 93,900 google hits (in all languages). Is found on dictionary.com as an English word. And Dirndl is found on 7,120 English-language pages. That's 7,120 against 281.
QED