This is pure speculation on my part but I have a few pointers.
- Spark is on v. 2.9.xxx. I know, there can always be a 2.10, but it does not look like Readdle does that.
- The iOS beta has been nothing but stability fixes for a long while.
- Some long standing editor bugs have been actively worked on (as per the Twitter feed) for a strange long while. (I think that may hide a change of underlying tech)
- Above all, the release notes in December have promised big things to come, asking the users to be a little bit patient.