In the latest update to Swifkey which is starting to rollout now, it appears that the sync feature that was turned off last month in the wake of some rather nasty cross-contamination with other accounts, has been switched back on.
The issue last month saw users using the Swiftkey sync feature seeing word suggestions and even email addresses appearing that weren’t from their synced accounts, or even in some case in their language. Swiftkey switched off sync to allow themselves time to fix the issue and it appears that it’s back in action for users updating to app version 18.104.22.168. The update was announced on their Swiftkey community site:
If you’re a Swiftkey user, you may want to try to update your Swiftkey app in Google Play, if there’s no update available then keep checking as the update appears to be rolling out a little slowly for some users.