When links are not present in the target wikipedia they are shown in grey in Content Translation (T193233). These unadapted links can be marked as red links when the user considers that they represent an article that make sense to be created in the target wiki.
However, is is also possible to leave the grey links without marking them as red in the translation. In that case, the expected behaviour is for these links to be published as regular text. Currently in version 2 (unlike version 1) the grey links are published as red links automatically.
This issue was reported by a translator in this comment.