timo
I consider that at the level of development of Diarium, the highest leverage would be to improve the search function.
A more powerful search would allow to create "virtual subsets" of your entries.
You wouldn't need multiple journals, or a specific notes section. With a powerful search, all can be handled with tags and keywords.
This is leveraged my the already excelente template functionality.
I use templates for each type of entries (meeting notes, exercise logs, sleep logs, day y reflection.... even capturing atomic notes for my zettelkasten.
BUT, the limits of the current search functionality are a ceiling.
Please consider improving the search function as a high impact intervention. Used properly, a robust search can substitute many other feature requests.