I believe the more specific you make a tool, the less likely it is to be used. Instead of doing all the work of creating a unique tool to construct timelines, create a tool that can be used to make timelines and other features like 3 act structure mapping, etc. Something similar to a "canvas" like Obsidian has or OneNote or countless other tools. Instead of just doing timelines, it can do all the things. Think in terms of creating a sandbox itself instead of creating individual toys for the sandbox. Users will find novel ways to make their own toys if they have a good sandbox.
Novlr is aesthetically simple and that is a big part of why I love it. Lean into that. I want the meat of what I do with Novlr to be getting my ass in the chair and writing words. Something like Scrivener, with all of its bells and whistles, distracts me from doing the thing I need to be doing which is writing a manuscript. Yea, I may get a false sense of productivity from creating characters profiles or detailed flora and fauna Wikipedia, but it's just that - false productivity. It's me avoiding the hard work of actually writing.
(Some) writers need an outline and nearly all writers need a place to jot down notes and ideas, that's about it. I think simply improving the existing tools we already have and adding capability to them is the way to go.

This is one of the big things missing (for me) at the moment with Novlr. I like using tools that help me draft outlines, synopsis, character sketches/arcs, notes, timelines and (in an ideal world) help me tie them together.

I have a project planned for the future that will require worldbuilding, and I would love to use these worldbuilding tools for it. Especially a timeline feature.

I wouldvlove a timeline feature and wiki-style note system!

Wiki-style note linking and the timeline feature would be my votes!

A glossary and language page would also be helpful for those of us creating new languages.