Perhaps it's attempting a discretionary ligature there, though my small brain isn't thinking of one that includes a d offhand. That would make sense with the italics aspect though, since things tend to get fancier there. It's not the only Google font that doesn't always play nice in this regard. I once subset Josefin for ebook and it dropped all the Xs, I believe.
That could be it. I didn't dive deep into the actual font file to see what the problem was because, quite frankly, there are better free options available (Allegreya and EB Garamond).
If we think of typefaces as music, then the font files are how that music is delivered. For whatever reason, Crimson Text (and others) is like sending a 45 record to someone who only has the means to play a Long Play record. They'll get sound, but it will be a bit of a mess.
Seriously, for anyone reading this post and formatting a book for print. If you aren't going to go with a professional typeface, then stick with EB Garamond or Allegreya. Either will serve your purposes and put out a nice looking print book without requiring a ton of work. (If you're willing to spend the money though, I highly recommend LFA Alumina,
LfA Aluminia Fonts it was re-designed from the original Electra designs, which is a typeface designed specifically for novels and really is beautiful on the page (plus it requires little to no adjustment)).