Thanks for the info. My guess is that you added content to the 20 entries with the bullet points on one device and then continued to use the app on both devices, without the sync being active. When you re-enabled the sync, Diarium has to deal with two individual databases (one from iOS and one from macOS) and merge them. Currently, the merging process (which happens on a "sync download", meaning the app downloads the remote database from iCloud) keeps the entire remote database, then grabs the last 7 entries (by entry date, not by modification date) from the local database and merges them to the remote database (which becomes the new local database).
This is a problem that only can happen when the sync is disabled and no sync is happening right before/after editing the journal. The problem in your case also was that you edited older entries which were then not considered in the merging process. I am afraid there is no way to recover this data - sorry.
I will look into the merging logic in more detail in the upcoming days and see if there is any possible problem when removing the "7 entry" limitation to further reduce the possibility of data loss.
I will also try to make it more clear to users that syncing will be disabled after the trial version runs out.
Sorry again for this problem and the loss of data - this shouldn't happen and I will work on fixing this.