Tim doesn't have that sticker on
the lady's page at Animobil. Tim, on your to-fix list?
There is a part (in the Paper-Stickers category) called "Stickers for Strass-Steine 5244 Inderin", part 30 80 4243. I just replace any instances of "Etikett" appearing in the German name with "Stickers for" to make the English name, and categorize it as "Paper-Stickers". Strass-Steine means rhinestones, so that's probably it.
The instructions for
5998 are online!