I also tried downgrading – but at a price. The reason is that Emeditor transfers certain settings from version 16.9.3 to version 17. Those settings cannot be recovered when downgrading – except if you didn’t run “Delete old settings”. In my case I made a mess with my settings (own fault, I didn’t realise at first).
In any case, if you didn’t run “Delete old settings”, then you can give downgrading a try (at your own risk):
http://files.emeditor.com/emed64_16.9.3.exe