Looks like it is abandoned https://todo.kde.org/?controller=task&action=show&task_id=161 Please, port spellcheck add-on to Plasma5 Reproducible: Always
We are tracking TODO items on that page, I don't want to have the same data twice, it gets complicated.
Note abandoned in this case means: "no-one has helped work on porting it" not "we have deliberately thrown it out"