I can live with this usage, each layout is a slice of the wiki (or a input for the wiki), let us read from or write to an aspect of the wiki.
I thought the Theme was about beautifying the layout using CSS (although we can’t limit it on this), and Palette was about changing variables in the CSS of the theme, and the Layout can be a total change of layout using HTML.
I’m treating layout manager as a way to mimic https://heptabase.com/ , notion and https://affine.pro/ , you can see my recent plugins are all about this. (https://github.com/tiddly-gittly/tiddlywiki-whiteboard and https://github.com/tiddly-gittly/tiddlywiki-calendar)
Add layout switcher page control button by linonetwo · Pull Request #7076 · TiddlyWiki/TiddlyWiki5 · GitHub
Also Do you want your wiki to have 3-10 different layouts?
I may create a launch-pad layout that can be used to open other layouts, looks like Square Home launcher
