Thanks puppyt for calling it to our attention and OscarTalks for providing a pet on this thread, viewtopic.php?f=92&t=3349. QuollWriter includes its own JRE java runtime environment and works fine under Xenialpup64, Bionicpup64 and Fossapup64 (maybe others).
Will download the libraries to use several languages (I think the major European --only as an after-thought did it occur to me not to just quickly choose English).
@OscarTalks: Don't be too quick to withdraw this as it appears to be a very well thought out application for fiction writers.
Although this is a beta release, starting it via a terminal the only complaint I received was "Can't create transparent stage, because your screen doesn't support alpha channel. You need to enable XComposite extension." Will have to see whether I need "transparent stage" and how complicated enabling the XComposite extension would be.