When creating an event in a timeline, you are able to link articles that relate to the event. The article categories you can link from are Characters, Organizations, Locations, Session Reports, Species, and Military Conflicts. There is also a dropdown for "Related Article," but this dropdown only shows your Generic article templates as options to choose from. It would be really cool to make that Related Article option allow any article to be linked.
I do see in the suggestion history that this request was denied due to the fact that adding additional elements to timelines does increase database load, but if expanding the dropdown or swapping it to something more like the existing article tag system (typing the @ symbol and tagging your chosen article) is possible, it would help a lot. I'm not a web designer by any means, but I do know that a lot has changed on WA recently, and wanted to bring the idea up anew.
Allowing more selection in the Related Articles linking category would let people link a lot more things that can be relevant on a timeline, such as inventions, discoveries, when documents were written, when things were built or founded (buildings, settlements, countries, or religions), or even the progression of languages if some worldbuilders want to get really spicy with their conlangs. So many options would be opened or expanded within timelines, and would probably make a lot of date-tracking more streamlined on the worldbuilder's end.
Other than expanding timeline usage, I don't know how much it would affect the rest of the site, but I know I, at least, would be much more encouraged to use timelines more consistently. It's hard for me to log everything in my timeline since I can't easily link the article I'm talking about, and as a very granular worldbuilder, this would make my work both easier and more exciting!
If this is a database problem, cast my votes towards fixing that problem first, then addressing this.
I like the idea of being able to add a tagged set of historical events to an article with some sort of mention/bbcode method. That way you could put it in your sidebar, similar to the events list (that's created from the bidirectional links).
During the timelines upgrade, Dimi explained that additional bi-directional links couldn't be supported. He wrote this manuscript entry about it. Unless there's been a breakthrough since Jan 2024, we likely still live within those limitations. We can add any article links we want to events with the mention system, they'd just be one-way instead of bi-directional. The event would link to those articles, but those articles won't automatically link to the event. I personally prefer this so I can control how and where a timeline of events appears in my articles. For those who prefer the auto-generated in-article timeline, I wonder if alternatives to bi-directional links could satisfy. Such as being able to embed an event list, optionally filtered by event tag. I don't know if something like that would be any more feasible.
Would suggest similar implementation for Chronicles if a distinction is necessary.