I just finished my 100 cards for the day in the German course. The 100th card was also my 20th new card of the day (Pferd).

I opened up the sidebar and the 80% and 100 badges are lit up, but not the 20 badge. My theory was that if you get the 20th card on your 100th card, the UI does not iterate through all the badges you've just earned, but just changes the status of one of them.

However, I ctrl+R'd the page and it still only shows the 80% and 100 badges. But I noticed it says I only learned 19 new words today.

I have been noting the new words in a spreadsheet to create mnemonics to help remember them (for example, a lion checking out some fabric in a store going "oh look at my stuff!" helps trigger in my head that fabric is der Stoff - the lion represents masculine gender, and stuff and Stoff sound similar, and he's looking at fabric, the meaning of Stoff). Looking at my list, I typed down 19 words.

So the sidebar seems to sometime show you've learned more words than you actually did. I've noticed when I do 100 cards sometimes it says "101" in the sidebar. So I'm guessing it's a UI issue that applies to more than one field.