Thanks for your feedback, @Hedda Gabler (eski).
This is a current limitation of the tool that can be problematic in some cases. This ticket captures the issue and a proposal for fixing it that goes along the lines of your suggestion. You can subscribe to the ticket to track the progress, or add any comment. There is also a proposal to automatically discard very old translations, that can also help to alleviate the problem of articles being blocked.
As far as I know there are not immediate plans to work in this area, but I linked your comment from the corresponding ticket for the team to be aware of it. So the only workaround I can think of is to copy the source article as a subpage of your user page and translate it.