You can do that in a comment, and you can also mark that comment as being about a translation mistake, which adds a different color and adds it to a list of issues." (It might also help to downvote the current translation.) Just keep in mind that comments are visible to all translators, so it’s more helpful to write them in English. You can find comments on the right, just like the translation memory. (I still find the Crowdin interface difficult to navigate, so if you struggle or have questions, feel free to ask.)