Generate a list of style definitions in a template

I think I would contemplate two things:

1: Use FrameMakers built-in template location (C:\Program Files\Adobe\Adobe FrameMaker 2022\Templates) and use that for storing the templates. A template for each function and a template for shared styles.

2: Use a naming convention for the paragraph styles, which will allow you to root them out when necessary.

3: FrameMakers catalog palettes have a neat function that allows you to sort the styles as you wish AND to exclude/include styles in the catalog. That might help you to, for instance, collect all the shared styles in group at the top.

Using the built-in template location is a great help, because it ensures that your templates are write protected, so you not accidentally changes anything. Also it is a great help for gradual change in template use.

I keep a style guide in a book inside an excluded folder. The guide keeps all styles grouped together for easier updating (for example, changing the color of all the headings). This guide can be linked to multiple projects and descriptions to why the styles are used could be added, if necessary, effectively turning it into a style-usage guide.

Without knowing too much about your workflow, I would probably isolate the use-specific into a separate guide for each project. And, as @Matt-Tech Comm Tools suggested, I would consolidate as many nearly identical styles as possible. For example, figure caption that is 11.5 and 11.25 pts.

I keep examples of my styles within the body of my template, allowing me to noodle with different combinations.

Sometimes it's helpful to keep them in a table, allowing me to easily choose, for instance, 5 heading styles for a global update.

If you're mired in too many formats, though, consider whether your audience will pick up the subtleties of the different styles in the first place. 

Ultimately, you can use Rick Quatro's FindChangeFormatsBatch script to simplify your paragraph assignments and remove unneeded styles.