It's a bit complicated to explain, but why not change the title screen image depending on when we are.
For example at the moment we are in Winter we could use a title screen of an ice biome... but some months later in Spring the image would automatically change to a birch forest.

That's already possible. To do this, make 4 layouts (spring, summer, autumn, winter) and only set a background image and nothing else (don't hide vanilla elements, etc.).
Now right-click the background of the editor while having one of the 4 layouts opened and click on Visibility Requirements. Enable the Real Time Month requirement and set it to show in the correct months (you can separate multiple months by comma).

This will make the layouts show in the correct season.