In Content Translation, user modifications on the translation are expected to be saved automatically. However, there are several circumstances in which users can do some modifications, go back to the dashboard and those modifications are lost when going back to the translation.
Adding links to the last edited paragraph. Adding links (using any means to do so) does not mark the document as "dirty" or trigger the saving process. Thus, if that is the last action the user does before leaving the document, the changes are lost.
Adding links in certain ways even if saving gets triggered. Adding an additional paragraph after the link manipulations may result in the modifications to be saved. But that seems to work only when links were added in a certain way. Links added with the preview card, and links marked as missing are not persisted unless another link is added using the link tool from the toolbar.